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nuttx/drivers/lcd/pcf8574_lcd_backpack.c

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/****************************************************************************
* drivers/lcd/pcf8574_lcd_backpack.c
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: dev@ziggurat29.com
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/ascii.h>
#include <nuttx/fs/fs.h>
#include <nuttx/lcd/slcd_codec.h>
#include <nuttx/lcd/pcf8574_lcd_backpack.h>
#ifndef CONFIG_LIB_SLCDCODEC
# error please also select Library Routines, Segment LCD CODEC
#endif
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* The PCF8574 is a 100 KHz device */
#define I2C_FREQ 100000
/* timing characteristics of the LCD interface */
#define DELAY_US_NYBBLE0 20
#define DELAY_US_NYBBLE1 10
#define DELAY_US_WRITE 40
#define DELAY_US_HOMECLEAR 1500
/* HD44780 commands */
#define CMD_CLEAR 0x01
#define CMD_HOME 0x02
#define CMD_CURSOR_ON_SOLID 0x0e
#define CMD_CURSOR_OFF 0x0c
#define CMD_CURSOR_ON_BLINK 0x0f
#define CMD_SET_CGADDR 0x40
#define CMD_SET_DDADDR 0x80
#define MAX_OPENCNT (255) /* Limit of uint8_t */
/****************************************************************************
* Private Types
****************************************************************************/
struct pcf8574_lcd_dev_s
{
FAR struct i2c_master_s *i2c; /* I2C interface */
struct pcf8574_lcd_backpack_config_s cfg; /* gpio configuration */
uint8_t bl_bit; /* current backlight bit */
uint8_t refs; /* Number of references */
uint8_t unlinked; /* We are unlinked, so teardown on last close */
sem_t sem_excl; /* mutex */
};
struct lcd_instream_s
{
struct lib_instream_s stream;
FAR const char *buffer;
ssize_t nbytes;
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Character driver methods */
static int pcf8574_lcd_open(FAR struct file *filep);
static int pcf8574_lcd_close(FAR struct file *filep);
static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t pcf8574_lcd_write(FAR struct file *filep,
FAR const char *buffer, size_t buflen);
static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence);
static int pcf8574_lcd_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
#ifndef CONFIG_DISABLE_POLL
static int pcf8574lcd_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup);
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int pcf8574_lcd_unlink(FAR struct inode *inode);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_pcf8574_lcd_fops =
{
pcf8574_lcd_open, /* open */
pcf8574_lcd_close, /* close */
pcf8574_lcd_read, /* read */
pcf8574_lcd_write, /* write */
pcf8574_lcd_seek, /* seek */
pcf8574_lcd_ioctl, /* ioctl */
#ifndef CONFIG_DISABLE_POLL
pcf8574lcd_poll, /* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
pcf8574_lcd_unlink /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: pca8574_write
*
* Description:
* primitive I2C write operation for the PCA8574, which is the IO expander
* device used on the board. The board essentially byte-bangs the
* parallel interface in nybble mode much as one might with a conventional
* GPIO based interface. The I2C interface simply sets the state of the
* 8 IO lines to control the 4 data, 3 control, and one for backlight,
* signals.
*
****************************************************************************/
static void pca8574_write(FAR struct pcf8574_lcd_dev_s *priv, uint8_t data)
{
struct i2c_config_s config;
int ret;
/* Set up the I2C configuration */
config.frequency = I2C_FREQ;
config.address = priv->cfg.addr;
config.addrlen = 7;
/* Write the value */
ret = i2c_write(priv->i2c, &config, &data, 1);
if (ret < 0)
{
lcdinfo("pca8574_write() failed: %d\n", ret);
return;
}
return;
}
/****************************************************************************
* Name: pca8574_read
*
* Description:
* primitive I2C read operation for the PCA8574, which is the IO expander
* device used on the board. The PCF8574 is 'interesting' in that it doesn't
* really have a data direction register, but instead the outputs are current-
* limited when high, so by setting an IO line high, you are also making it
* an input. Consequently, before using this method, you'll need to perform a
* pca8574_write() setting the bits you are interested in reading to 1's,
* then call this method.
*
****************************************************************************/
static int pca8574_read(FAR struct pcf8574_lcd_dev_s *priv, uint8_t* data)
{
struct i2c_config_s config;
int ret;
/* Set up the I2C configuration */
config.frequency = I2C_FREQ;
config.address = priv->cfg.addr;
config.addrlen = 7;
/* Read the value */
ret = i2c_read(priv->i2c, &config, data, 1);
if (ret < 0)
{
lcdinfo("pca8574_read() failed: %d\n", ret);
}
return ret;
}
/****************************************************************************
* Name: lcd_backlight
*
* Description:
* turn on, or off, the LCD backlight
*
****************************************************************************/
static void lcd_backlight(FAR struct pcf8574_lcd_dev_s *priv, bool blOn)
{
uint8_t data;
data = ((blOn && priv->cfg.bl_active_high) ||
(!blOn && !priv->cfg.bl_active_high)) ? (1 << priv->cfg.bl) : 0;
pca8574_write(priv, data);
priv->bl_bit = data;
}
/****************************************************************************
* Name: rc2addr
*
* Description:
* This converts a row/column pair to a screen memory address.
*
****************************************************************************/
static inline uint8_t rc2addr(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t row, uint8_t col)
{
if (row < 2)
{
/* 1 and 2 line displays are simple; line0 @ 0x00, line1 @ 0x40 */
return row * 0x40 + col;
}
else
{
/* 4 line displays are intersting; third line really is a continuation
* of first line, and fourth line is a continuation of second.
*/
return (row - 2) * 0x40 + (col + priv->cfg.cols);
}
}
/****************************************************************************
* Name: addr2rc
*
* Description:
* This converts a screen memory address to a row/column pair.
*
****************************************************************************/
static inline void addr2rc(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t addr, uint8_t* row, uint8_t* col)
{
*row = addr / 0x40;
*col = addr % 0x40;
if (*col >= priv->cfg.cols)
{
/* 4 line displays have third and fourth lines really as continuation
* of first and second.
*/
*row += 2;
*col -= priv->cfg.cols;
}
}
/****************************************************************************
* Name: prepare_nybble
*
* Description:
* This is a bit tedious, but scramble the bits of the nybble into position
* as per this board's particular wiring. Most boards are either on the
* top four bits, or bottom four, so a shift would do typically in those
* cases, but this gives us ultimate flexibility.
*
****************************************************************************/
uint8_t prepare_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t nybble)
{
uint8_t lcddata = 0;
if (nybble & 0x08)
{
lcddata |= (1 << priv->cfg.d7);
}
if (nybble & 0x04)
{
lcddata |= (1 << priv->cfg.d6);
}
if (nybble & 0x02)
{
lcddata |= (1 << priv->cfg.d5);
}
if (nybble & 0x01)
{
lcddata |= (1 << priv->cfg.d4);
}
return lcddata;
}
/****************************************************************************
* Name: unprepare_nybble
*
* Description:
* This is the opposite of prepare_nybble(), and is used to unscramble bits
* when reading data from the display, as per board wiring.
*
****************************************************************************/
uint8_t unprepare_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t lcddata)
{
uint8_t data = 0;
if (lcddata & (1 << priv->cfg.d7))
{
data |= 0x08;
}
if (lcddata & (1 << priv->cfg.d6))
{
data |= 0x04;
}
if (lcddata & (1 << priv->cfg.d5))
{
data |= 0x02;
}
if (lcddata & (1 << priv->cfg.d4))
{
data |= 0x01;
}
return data;
}
/****************************************************************************
* Name: latch_nybble
*
* Description:
* Latch a nybble on the LCD bus. This is done for each of two halves of a
* write operation in 4-bit mode. The 'rs' param is false for command
* transfers, and true for data transfers.
*
****************************************************************************/
static void latch_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t nybble,
bool rs)
{
uint8_t lcddata;
uint8_t en_bit;
uint8_t rs_bit;
en_bit = 1 << priv->cfg.en;
rs_bit = rs ? (1 << priv->cfg.rs) : 0;
/* Put the nybble, preserving backlight, reset R/~W and maybe RS */
lcddata = prepare_nybble(priv, nybble) | priv->bl_bit | rs_bit;
pca8574_write(priv, lcddata);
/* Now set EN */
lcddata |= en_bit;
pca8574_write(priv, lcddata);
up_udelay(DELAY_US_NYBBLE0); /* setup */
/* Latch on EN falling edge */
lcddata &= ~en_bit;
pca8574_write(priv, lcddata);
up_udelay(DELAY_US_NYBBLE1); /* hold */
}
/****************************************************************************
* Name: load_nybble
*
* Description:
* Load a nybble from the LCD bus. This is done for each of two halves of a
* read operation in 4-bit mode. The 'rs' param is false for command
* transfers (the only one is to read status and the address register), and
* true for data transfers.
*
****************************************************************************/
static uint8_t load_nybble(FAR struct pcf8574_lcd_dev_s *priv, bool rs)
{
uint8_t lcddata;
uint8_t en_bit;
uint8_t rs_bit;
uint8_t rw_bit;
uint8_t data;
en_bit = 1 << priv->cfg.en;
rs_bit = rs ? (1 << priv->cfg.rs) : 0;
rw_bit = 1 << priv->cfg.rw;
/* Put highs on the data lines, preserve, set R/~W and maybe RS */
lcddata = prepare_nybble(priv, 0x0f) | priv->bl_bit | rw_bit | rs_bit;
pca8574_write(priv, lcddata);
/* Now set EN */
lcddata |= en_bit;
pca8574_write(priv, lcddata);
up_udelay(DELAY_US_NYBBLE0); /* setup */
/* Now read the data */
pca8574_read(priv, &data);
data = unprepare_nybble(priv, data);
/* Transaction completed on EN falling edge */
lcddata &= ~en_bit;
pca8574_write(priv, lcddata);
up_udelay(DELAY_US_NYBBLE1); /* hold */
return data;
}
/****************************************************************************
* Name: lcd_putcmd
*
* Description:
* Write a command to the LCD. Most of the time this is done in nybble
* mode in two phases, but in special cases (like initialization) we do not
* do two phases.
*
****************************************************************************/
static void lcd_putcmd(FAR struct pcf8574_lcd_dev_s *priv, uint8_t data)
{
latch_nybble(priv, data >> 4, false);
latch_nybble(priv, data, false);
up_udelay(DELAY_US_WRITE);
}
/****************************************************************************
* Name: lcd_putdata
*
* Description:
* Write a byte to the LCD. This is used both for screen data and for
* character generator data, depending on a previous command that selected
* which ever is the destination.
*
****************************************************************************/
static inline void lcd_putdata(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t data)
{
latch_nybble(priv, data >> 4, true);
latch_nybble(priv, data, true);
up_udelay(DELAY_US_WRITE);
}
/****************************************************************************
* Name: lcd_getdata
*
* Description:
* Read a data byte from the LCD.
*
****************************************************************************/
static inline uint8_t lcd_getdata(FAR struct pcf8574_lcd_dev_s *priv)
{
uint8_t data;
data = (load_nybble(priv, true) << 4) | load_nybble(priv, true);
return data;
}
/****************************************************************************
* Name: lcd_getcmd
*
* Description:
* Read a command byte from the LCD. There really is only one such read:
* get 'busy' status, and current address value.
*
****************************************************************************/
static inline uint8_t lcd_getcmd(FAR struct pcf8574_lcd_dev_s *priv)
{
uint8_t data;
data = (load_nybble(priv, false) << 4) | load_nybble(priv, false);
return data;
}
/****************************************************************************
* Name: lcd_read_busy_addr
*
* Description:
* Read the busy flag, and, optionally, the current value of the address
* register (data or character generator dependent on a previous command).
*
****************************************************************************/
static bool lcd_read_busy_addr(FAR struct pcf8574_lcd_dev_s *priv, uint8_t* addr)
{
uint8_t data = lcd_getcmd(priv);
if (NULL != addr)
{
*addr = data & 0x7f;
}
return (data & 0x80) ? true : false;
}
/****************************************************************************
* Name: lcd_init
*
* Description:
* perform the initialization sequence to get the LCD into a known state.
*
****************************************************************************/
static void lcd_init(FAR struct pcf8574_lcd_dev_s *priv)
{
/* Wait for more than 15 ms after Vcc for the LCD to stabilize */
usleep(50000);
/* Perform the init sequence. This sequence of commands is constructed so
* that it will get the device into nybble mode irrespective of what state
* the device is currently in (could be 8 bit, 4 bit nyb 0, 4 bit nyb 1).
* By sending the 'set 8-bit mode' three times, we will definitely end up
* in 8 bit mode, and then we can reliably transition to 4 bit mode for
* the remainder of operations.
*/
/* Send Command 0x30, set 8-bit mode, and wait > 4.1 ms */
latch_nybble(priv, 0x30>>4, false);
usleep(5000);
/* Send Command 0x30, set 8-bit mode, and wait > 100 us */
latch_nybble(priv, 0x30>>4, false);
usleep(5000);
/* Send Command 0x30, set 8-bit mode */
latch_nybble(priv, 0x30>>4, false);
usleep(200);
/* now Function set: Set interface to be 4 bits long (only 1 cycle write for the first time). */
latch_nybble(priv, 0x20>>4, false);
usleep(5000);
/* Function set: DL=0;Interface is 4 bits, N=1 (2 Lines), F=0 (5x8 dots font) */
lcd_putcmd(priv, 0x28);
/* Display Off: D=0 (Display off), C=0 (Cursor Off), B=0 (Blinking Off) */
lcd_putcmd(priv, 0x08);
/* Display Clear */
lcd_putcmd(priv, CMD_CLEAR);
up_udelay(DELAY_US_HOMECLEAR); /* clear needs extra time */
/* Entry Mode Set: I/D=1 (Increment), S=0 (No shift) */
lcd_putcmd(priv, 0x06);
/* Display On, Cursor Off */
lcd_putcmd(priv, 0x0C);
}
/****************************************************************************
* Name: lcd_create_char
*
* Description:
* This creates a custom character pattern. There can be 8 5x8 patterns.
* The bitmap proceeds top to bottom, msb-lsb, and is right justified (i.e.
* only bits 4-0 are used). By convention, you are meant to always leave the
* last line (byte) zero so that the cursor can use this line, but this is
* not strictly required.
*
* Parameters:
* priv - device instance
* idxchar - which character is being imaged; 0 - 7
* chardata - the character image bitmap; must be 8 bytes always
*
****************************************************************************/
static void lcd_create_char(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t idxchar, const uint8_t *chardata)
{
int nIdx;
uint8_t addr;
(void)lcd_read_busy_addr(priv, &addr);
lcd_putcmd(priv, CMD_SET_CGADDR | (idxchar << 3)); /* set CGRAM address */
for (nIdx = 0; nIdx < 8; ++nIdx)
{
lcd_putdata(priv, chardata[nIdx]);
}
lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* restore DDRAM address */
}
/****************************************************************************
* Name: lcd_set_curpos
*
* Description:
* This sets the cursor position based on row, column addressing.
*
* Parameters:
* priv - device instance
* row - row position
* col - column position
*
****************************************************************************/
static void lcd_set_curpos(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t row, uint8_t col)
{
uint8_t addr;
addr = rc2addr(priv, row, col);
lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* set DDRAM address */
}
/****************************************************************************
* Name: lcd_get_curpos
*
* Description:
* This gets the cursor position based on row, column addressing.
*
* Parameters:
* priv - device instance
* row - row position
* col - column position
*
****************************************************************************/
static void lcd_get_curpos(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t *row, uint8_t *col)
{
uint8_t addr;
(void)lcd_read_busy_addr(priv, &addr);
addr2rc(priv, addr, row, col);
}
/****************************************************************************
* Name: lcd_scroll_up
*
* Description:
* Scroll the display up, and clear the new (last) line.
*
****************************************************************************/
static void lcd_scroll_up(FAR struct pcf8574_lcd_dev_s *priv)
{
uint8_t *data;
int nRow;
int nCol;
data = (uint8_t *)malloc(priv->cfg.cols);
if (NULL == data)
{
lcdinfo("Failed to allocate buffer in lcd_scroll_up()\n");
return;
}
for (nRow = 1; nRow < priv->cfg.rows; ++nRow)
{
lcd_set_curpos(priv, nRow, 0);
for (nCol = 0; nCol < priv->cfg.cols; ++nCol)
{
data[nCol] = lcd_getdata(priv);
}
lcd_set_curpos(priv, nRow - 1, 0);
for (nCol = 0; nCol < priv->cfg.cols; ++nCol)
{
lcd_putdata(priv, data[nCol]);
}
}
lcd_set_curpos(priv, priv->cfg.rows - 1, 0);
for (nCol = 0; nCol < priv->cfg.cols; ++nCol)
{
lcd_putdata(priv, ' ');
}
lcd_set_curpos(priv, priv->cfg.rows - 1, 0);
free(data);
return;
}
/****************************************************************************
* Name: lcd_codec_action
*
* Description:
* Perform an 'action' as per the Segment LCD codec.
*
* Parameters:
* priv - device instance
* code - SLCD code action code
* count - count param for those actions that take it
*
****************************************************************************/
static void lcd_codec_action(FAR struct pcf8574_lcd_dev_s *priv,
enum slcdcode_e code, uint8_t count)
{
switch (code)
{
/* Erasure */
case SLCDCODE_BACKDEL: /* Backspace (backward delete) N characters */
{
if (count <= 0) /* silly case */
break;
else
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
if (count > col) /* saturate to preceding columns available */
{
count = col;
}
lcd_set_curpos(priv, row, col-count);
}
/* ... and conscientiously fall through to next case ... */
}
case SLCDCODE_FWDDEL: /* Delete (forward delete) N characters, moving text */
{
if (count <= 0) /* silly case */
{
break;
}
else
{
uint8_t row;
uint8_t col;
uint8_t start;
uint8_t end;
uint8_t nIdx;
uint8_t data;
lcd_get_curpos(priv, &row, &col);
start = col + count;
if (start >= priv->cfg.cols) /* silly case of nothing left */
{
break;
}
end = start + count;
if (end > priv->cfg.cols) /* saturate */
{
end = priv->cfg.cols;
}
for(nIdx = col; nIdx < end; ++start, ++nIdx) /* much like memmove */
{
lcd_set_curpos(priv, row, start);
data = lcd_getdata(priv);
lcd_set_curpos(priv, row, nIdx);
lcd_putdata(priv, data);
}
for(;nIdx < priv->cfg.cols; ++nIdx) /* much like memset */
{
lcd_putdata(priv, ' ');
}
lcd_set_curpos(priv, row, col);
}
}
break;
case SLCDCODE_ERASE: /* Erase N characters from the cursor position */
if (count > 0)
{
uint8_t row;
uint8_t col;
uint8_t end;
uint8_t nIdx;
lcd_get_curpos(priv, &row, &col);
end = col + count;
if (end > priv->cfg.cols)
{
end = priv->cfg.cols;
}
for (nIdx = col; nIdx < end; ++nIdx)
{
lcd_putdata(priv, ' ');
}
lcd_set_curpos(priv, row, col);
}
break;
case SLCDCODE_CLEAR: /* Home the cursor and erase the entire display */
{
lcd_putcmd(priv, CMD_CLEAR);
up_udelay(DELAY_US_HOMECLEAR); /* clear needs extra time */
}
break;
case SLCDCODE_ERASEEOL: /* Erase from the cursor position to the end of line */
{
uint8_t row;
uint8_t col;
uint8_t nIdx;
lcd_get_curpos(priv, &row, &col);
for (nIdx = col; nIdx < priv->cfg.cols; ++nIdx)
{
lcd_putdata(priv, ' ');
}
lcd_set_curpos(priv, row, col);
}
break;
/* Cursor movement */
case SLCDCODE_LEFT: /* Cursor left by N characters */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
if (count > col)
{
col = 0;
}
else
{
col -= count;
}
lcd_set_curpos(priv, row, col);
}
break;
case SLCDCODE_RIGHT: /* Cursor right by N characters */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
col += count;
if (col >= priv->cfg.cols)
{
col = priv->cfg.cols-1;
}
lcd_set_curpos(priv, row, col);
}
break;
case SLCDCODE_UP: /* Cursor up by N lines */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
if (count > row)
{
row = 0;
}
else
{
row -= count;
}
lcd_set_curpos(priv, row, col);
}
break;
case SLCDCODE_DOWN: /* Cursor down by N lines */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
row += count;
if (row >= priv->cfg.rows)
{
row = priv->cfg.rows - 1;
}
lcd_set_curpos(priv, row, col);
}
break;
case SLCDCODE_HOME: /* Cursor home */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
lcd_set_curpos(priv, row, 0);
}
break;
case SLCDCODE_END: /* Cursor end */
{
uint8_t row;
uint8_t col;
lcd_get_curpos(priv, &row, &col);
lcd_set_curpos(priv, row, priv->cfg.cols - 1);
}
break;
case SLCDCODE_PAGEUP: /* Cursor up by N pages */
case SLCDCODE_PAGEDOWN: /* Cursor down by N pages */
break; /* Not supportable on this SLCD */
/* Blinking */
case SLCDCODE_BLINKSTART: /* Start blinking with current cursor position */
lcd_putcmd(priv, CMD_CURSOR_ON_BLINK);
break;
case SLCDCODE_BLINKEND: /* End blinking after the current cursor position */
case SLCDCODE_BLINKOFF: /* Turn blinking off */
lcd_putcmd(priv, CMD_CURSOR_OFF);
break; /* Not implemented */
/* These are actually unreportable errors */
default:
case SLCDCODE_NORMAL: /* Not a special keycode */
break;
}
}
/****************************************************************************
* Name: lcd_getstream
*
* Description:
* Get one character from the LCD codec stream.
*
****************************************************************************/
static int lcd_getstream(FAR struct lib_instream_s *instream)
{
FAR struct lcd_instream_s *lcdstream = (FAR struct lcd_instream_s *)instream;
if (lcdstream->nbytes > 0)
{
lcdstream->nbytes--;
lcdstream->stream.nget++;
return (int)*lcdstream->buffer++;
}
return EOF;
}
/****************************************************************************
* Name: lcd_fpos_to_curpos
*
* Description:
* Convert a file logical offset to a screen cursor pos (row,col). This
* discounts 'synthesized' line feeds at the end of screen lines.
*
****************************************************************************/
static void lcd_fpos_to_curpos(FAR struct pcf8574_lcd_dev_s *priv,
off_t fpos, uint8_t *row, uint8_t *col, bool* onlf)
{
int virtcols;
virtcols = (priv->cfg.cols + 1);
/* Determine if this is a 'virtual' position (on the synthetic LF) */
*onlf = (priv->cfg.cols == fpos % virtcols);
/* Adjust off any preceding synthetic LF's to get linear position */
fpos -= fpos / virtcols;
/* Compute row/col from linear position */
*row = fpos / priv->cfg.cols;
*col = fpos % priv->cfg.cols;
}
/****************************************************************************
* Name: lcd_curpos_to_fpos
*
* Description:
* Convert a screen cursor pos (row,col) to a file logical offset. This
* includes 'synthesized' line feeds at the end of screen lines.
*
****************************************************************************/
static void lcd_curpos_to_fpos(FAR struct pcf8574_lcd_dev_s *priv,
uint8_t row, uint8_t col, off_t* fpos)
{
/* the logical file position is the linear position plus any synthetic LF */
*fpos = (row * priv->cfg.cols) + col + row;
}
/****************************************************************************
* Name: pcf8574_lcd_open
*
* Description:
* requisite device 'open' method; we don't do anything special
*
****************************************************************************/
static int pcf8574_lcd_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
/* Increment the reference count */
sem_wait(&priv->sem_excl);
if (priv->refs == MAX_OPENCNT)
{
return -EMFILE;
}
else
{
priv->refs++;
}
sem_post(&priv->sem_excl);
return OK;
}
/****************************************************************************
* Name: pcf8574_lcd_close
*
* Description:
* requisite device 'close' method; we don't do anything special
*
****************************************************************************/
static int pcf8574_lcd_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
int ret;
/* Decrement the reference count */
sem_wait(&priv->sem_excl);
if (priv->refs == 0)
{
ret = -EIO;
}
else
{
priv->refs--;
/* If we had previously unlinked, but there were open references at the
* time, we need to do the final teardown now.
*/
if (priv->refs == 0 && priv->unlinked)
{
/* We have no real teardown at present */
}
ret = OK;
}
sem_post(&priv->sem_excl);
return ret;
}
/****************************************************************************
* Name: pcf8574_lcd_read
*
* Description:
* This simply reads as much of the display memory as possible. This is
* generally not very interesting, but we do it in a way that allows us to
* 'cat' the LCD contents via the shell.
*
****************************************************************************/
static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
int nIdx;
uint8_t addr;
uint8_t row;
uint8_t col;
bool onlf;
sem_wait(&priv->sem_excl);
/* Get current cursor position so we can restore it */
(void)lcd_read_busy_addr(priv, &addr);
/* Convert file position to row/col address and position DDADDR there */
lcd_fpos_to_curpos(priv, filep->f_pos, &row, &col, &onlf);
lcd_set_curpos(priv, row, col);
/* Read as much of the display as possible */
nIdx = 0;
while (nIdx < buflen && row < priv->cfg.rows)
{
/* Synthesize end-of-line LF and advance to start of next row */
if (onlf)
{
/* Synthesize LF for all but last row */
if ( row < priv->cfg.rows-1)
{
buffer[nIdx] = '\x0a';
onlf = false;
++filep->f_pos;
++nIdx;
}
++row;
col = 0;
continue;
}
/* If we are at start of line we will need to update DDRAM address */
if (0 == col)
{
lcd_set_curpos(priv, row, 0);
}
buffer[nIdx] = lcd_getdata(priv);
++filep->f_pos;
++nIdx;
++col;
/* If we are now at the end of a line, we setup for the synthetic LF */
if (priv->cfg.cols == col)
{
onlf = true;
}
}
lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* Restore DDRAM address */
sem_post(&priv->sem_excl);
return nIdx;
}
/****************************************************************************
* Name: pcf8574_lcd_write
*
* Description:
* Output a sequence of characters to the device.
*
****************************************************************************/
static ssize_t pcf8574_lcd_write(FAR struct file *filep,
FAR const char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
struct lcd_instream_s instream;
uint8_t row;
uint8_t col;
struct slcdstate_s state;
enum slcdret_e result;
uint8_t ch;
uint8_t count;
sem_wait(&priv->sem_excl);
/* Initialize the stream for use with the SLCD CODEC */
instream.stream.get = lcd_getstream;
instream.stream.nget = 0;
instream.buffer = buffer;
instream.nbytes = buflen;
/* Get the current cursor position now; we'll keep track of it as we go */
lcd_get_curpos(priv, &row, &col);
/* Now decode and process every byte in the input buffer */
memset(&state, 0, sizeof(struct slcdstate_s));
while ((result = slcd_decode(&instream.stream, &state, &ch, &count)) != SLCDRET_EOF)
{
if (result == SLCDRET_CHAR) /* A normal character was returned */
{
/* Check for ASCII control characters */
if (ch == ASCII_TAB)
{
lcd_putcmd(priv, CMD_CURSOR_ON_BLINK);
}
else if (ch == ASCII_VT)
{
/* Turn the backlight on */
lcd_backlight(priv, true);
}
else if (ch == ASCII_FF)
{
/* Turn the backlight off */
lcd_backlight(priv, false);
}
else if (ch == ASCII_CR)
{
/* Perform a Home */
lcd_putcmd(priv, CMD_HOME);
up_udelay(DELAY_US_HOMECLEAR); /* home needs extra time */
row = 0;
col = 0;
}
else if (ch == ASCII_SO)
{
lcd_putcmd(priv, CMD_CURSOR_OFF);
}
else if (ch == ASCII_SI)
{
/* Perform the re-initialize */
lcd_init(priv);
row = 0;
col = 0;
}
else if (ch == ASCII_LF)
{
/* unixian line term; go to start of next line */
row += 1;
if (row >= priv->cfg.rows)
{
lcd_scroll_up(priv);
row = priv->cfg.rows - 1;
}
col = 0;
lcd_set_curpos(priv, row, col);
}
else if (ch == ASCII_BS)
{
/* Perform the backward deletion */
lcd_codec_action(priv, SLCDCODE_BACKDEL, 1);
lcd_get_curpos(priv, &row, &col);
}
else if (ch == ASCII_DEL)
{
/* Perform the forward deletion */
lcd_codec_action(priv, SLCDCODE_FWDDEL, 1);
lcd_get_curpos(priv, &row, &col);
}
else
{
/* All others are fair game. See if we need to wrap line. */
if (col >= priv->cfg.cols)
{
row += 1;
if (row >= priv->cfg.rows)
{
lcd_scroll_up(priv);
row = priv->cfg.rows - 1;
}
col = 0;
lcd_set_curpos(priv, row, col);
}
lcd_putdata(priv, ch);
++col;
}
}
else /* (result == SLCDRET_SPEC) */ /* A special SLCD action was returned */
{
lcd_codec_action(priv, (enum slcdcode_e)ch, count);
/* we can't know what happened, so it's easier just to re-inquire
* as to where we are.
*/
lcd_get_curpos(priv, &row, &col);
}
}
/* Wherever we wound up, update our logical file pos to reflect it */
lcd_curpos_to_fpos(priv, row, col, &filep->f_pos);
sem_post(&priv->sem_excl);
return buflen;
}
/****************************************************************************
* Name: pcf8574_lcd_seek
*
* Description:
* Seek the logical file pointer to the specified position. This is
* probably not very interesting except possibly for (SEEK_SET, 0) to
* rewind the pointer for a subsequent read().
* The file pointer is logical, and includes synthesized LF chars at the
* end of the display lines.
*
****************************************************************************/
static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
int maxpos;
sem_wait(&priv->sem_excl);
maxpos = priv->cfg.rows * priv->cfg.cols + (priv->cfg.rows - 1);
switch (whence)
{
case SEEK_CUR:
filep->f_pos += offset;
if (filep->f_pos > maxpos)
filep->f_pos = maxpos;
break;
case SEEK_SET:
filep->f_pos = offset;
if (filep->f_pos > maxpos)
filep->f_pos = maxpos;
break;
case SEEK_END:
filep->f_pos = maxpos;
break;
default:
/* Return EINVAL if the whence argument is invalid */
filep->f_pos = -EINVAL;
}
sem_post(&priv->sem_excl);
return filep->f_pos;
}
/****************************************************************************
* Name: pcf8574_lcd_ioctl
*
* Description:
* Perform device operations that are outside the standard I/O model.
*
****************************************************************************/
static int pcf8574_lcd_ioctl(FAR struct file *filep, int cmd,
unsigned long arg)
{
switch (cmd)
{
case SLCDIOC_GETATTRIBUTES: /* SLCDIOC_GETATTRIBUTES: Get the attributes of the SLCD */
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
FAR struct slcd_attributes_s *attr = (FAR struct slcd_attributes_s *)((uintptr_t)arg);
lcdinfo("SLCDIOC_GETATTRIBUTES:\n");
if (!attr)
{
return -EINVAL;
}
attr->nrows = priv->cfg.rows;
attr->ncolumns = priv->cfg.cols;
attr->nbars = 0;
attr->maxcontrast = 0;
attr->maxbrightness = 1; /* 'brightness' for us is the backlight */
}
break;
case SLCDIOC_CURPOS: /* SLCDIOC_CURPOS: Get the SLCD cursor position */
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
FAR struct slcd_curpos_s *attr = (FAR struct slcd_curpos_s *)((uintptr_t)arg);
uint8_t row;
uint8_t col;
sem_wait(&priv->sem_excl);
lcd_get_curpos(priv, &row, &col);
attr->row = row;
attr->column = col;
sem_post(&priv->sem_excl);
}
break;
case SLCDIOC_GETBRIGHTNESS: /* Get the current brightness setting */
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
bool bOn;
bOn = (priv->bl_bit && priv->cfg.bl_active_high) || (!priv->bl_bit && !priv->cfg.bl_active_high);
*(int*)((uintptr_t)arg) = bOn ? 1 : 0;
}
break;
case SLCDIOC_SETBRIGHTNESS: /* Set the brightness to a new value */
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
sem_wait(&priv->sem_excl);
lcd_backlight(priv, arg ? true : false);
sem_post(&priv->sem_excl);
}
break;
case SLCDIOC_CREATECHAR: /* Create a custom character pattern */
{
FAR struct inode *inode = filep->f_inode;
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
FAR struct slcd_createchar_s *attr = (FAR struct slcd_createchar_s *)((uintptr_t)arg);
sem_wait(&priv->sem_excl);
lcd_create_char(priv, attr->idx, attr->bmp);
sem_post(&priv->sem_excl);
}
break;
case SLCDIOC_SETBAR: /* SLCDIOC_SETBAR: Set bars on a bar display */
case SLCDIOC_GETCONTRAST: /* SLCDIOC_GETCONTRAST: Get the current contrast setting */
case SLCDIOC_SETCONTRAST: /* SLCDIOC_SETCONTRAST: Set the contrast to a new value */
default:
return -ENOTTY;
}
return OK;
}
/****************************************************************************
* Name: pcf8574lcd_poll
****************************************************************************/
#ifndef CONFIG_DISABLE_POLL
static int pcf8574lcd_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
if (setup)
{
/* Data is always available to be read */
fds->revents |= (fds->events & (POLLIN|POLLOUT));
if (fds->revents != 0)
{
sem_post(fds->sem);
}
}
return OK;
}
#endif
/****************************************************************************
* Name: pcf8574_lcd_unlink
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int pcf8574_lcd_unlink(FAR struct inode *inode)
{
FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
int ret = OK;
sem_wait(&priv->sem_excl);
priv->unlinked = true;
/* If there are no open references to the driver then tear it down now */
if (priv->refs == 0)
{
/* We have no real teardown at present */
ret = OK;
}
sem_post(&priv->sem_excl);
return ret;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pcf8574_lcd_backpack_register
*
* Description:
* Register a character driver that is an I2C LCD 'backpack' for the
* ever-popular HD44780 based 16x2 LCD via pcf8574 I2C IO expander.
*
****************************************************************************/
int pcf8574_lcd_backpack_register(FAR const char *devpath,
FAR struct i2c_master_s *i2c,
FAR struct pcf8574_lcd_backpack_config_s *cfg)
{
FAR struct pcf8574_lcd_dev_s *priv;
int ret;
/* Sanity check on geometry */
if (cfg->rows < 1 || cfg->rows > 4)
{
lcdinfo("Display rows must be 1-4\n");
return -EINVAL;
}
if ((cfg->cols < 1 || cfg->cols > 64) || (cfg->rows == 4 && cfg->cols > 32))
{
lcdinfo("Display cols must be 1-64, and may not be part of a 4x40 configuration\n");
return -EINVAL;
}
/* Initialize the device structure */
priv = (FAR struct pcf8574_lcd_dev_s *)kmm_malloc(sizeof(struct pcf8574_lcd_dev_s));
if (!priv)
{
lcdinfo("Failed to allocate instance\n");
return -ENOMEM;
}
priv->i2c = i2c;
priv->cfg = *cfg;
priv->bl_bit = priv->cfg.bl_active_high ? 0 : (1 << priv->cfg.bl);
priv->refs = 0;
priv->unlinked = false;
sem_init(&priv->sem_excl, 0, 1);
/* Initialize */
lcd_init(priv);
/* Register the character driver */
ret = register_driver(devpath, &g_pcf8574_lcd_fops, 0666, priv);
if (ret < 0)
{
lcdinfo("Failed to register driver: %d\n", ret);
kmm_free(priv);
}
lcdinfo("pcf8574_lcd_backpack driver loaded successfully!\n");
return ret;
}
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