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README
======
This README file discusses the port of NuttX to the Silicon Labs EFM32™
Gecko Starter Kit (EFM32-G8XX-STK). The Gecko Starter Kit features:
• EFM32G890F128 MCU with 128 kB flash and 16 kB RAM
• 32.768 kHz crystal (LXFO)
• 32 MHz crystal (HXFO)
• Advanced Energy Monitoring
• Touch slider
• 4x40 LCD
• 4 User LEDs
• 2 pushbutton switches
• Reset button and a switch to disconnect the battery.
• On-board SEGGER J-Link USB emulator
• ARM 20 pin JTAG/SWD standard Debug in/out connector
CONTENTS
=======
• Status
• LEDs
• Serial Console
• Using the J-Link GDB Server
• Configurations
STATUS
======
2014-10-28. At this point all basic boot operations are successful: The
LEDs work and the application tasks appear to be successfully started.
LED2 is on and LED0 is glowing (meaning that interrupts are being
processed). However, I get no output on PE0. Data appears to be sent
(at least by efm32_lowputc()). However, no signal activity is present
on PE0.
2014-10-29: The NuttX is running on the EFM32 Gecko Starter Kit. There
are not many peripherals to test in that configuration, but the NuttShell
(NSH) is working over LEUART0 at 2400 baud (certainly that could go up
to 4800. The documentation says that 9600 is also possible on the
LEUART, but I am not sure how).
I originally planned to use UART0 at 115200 baud, but I never could get
any output from the board. I reviewd my pin configuration and clocking
carefully and the USART seems to think it is working correctly. So I
am thinking that there is some board issue that prohibits that option
(probably because UART0 is used with the board controller???). Pins
are not available for other U[S]ARTs on the board.
DMA and USART-based SPI supported are included, but not yet tested.
2014-10-29: Calibrated the delays loops.
2014-10-29: The start-up time is long -- about a second. I have traced
this to the default delay in bringing up the LFCLK in efm32_clockconfig.
The default, reset setting of the LFXOTIMEOUT field of the CMU_CTRL
register is 3 which corresponds to a delay of 32768 cycles, or a full
second. I have not experimented to see if this delay can be reduced.
LEDs
====
The EFM32 Gecko Start Kit has four yellow LEDs. These LEDs are connected
as follows:
------------------------------------- --------------------
EFM32 PIN BOARD SIGNALS
------------------------------------- --------------------
C0/USART1_TX#0/PCNT0_S0IN#2/ACMP0_CH0 MCU_PC0 UIF_LED0
C1/USART1_RX#0/PCNT0_S1IN#2/ACMP0_CH1 MCU_PC1 UIF_LED1
C2/USART2_TX#0/ACMP0_CH2 MCU_PC2 UIF_LED2
C3/USART2_RX#0/ACMP0_CH3 MCU_PC3 UIF_LED3
------------------------------------- --------------------
All LEDs are grounded and so are illuminated by outputting a high
value to the LED.
These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is
defined. In that case, the usage by the board port is defined in
include/board.h and src/efm32_autoleds.c. The LEDs are used to
encode OS-related events as follows:
SYMBOL Meaning LED0* LED1 LED2 LED3
----------------- ----------------------- ------ ----- ----- ------
LED_STARTED NuttX has been started ON OFF OFF OFF
LED_HEAPALLOCATE Heap has been allocated OFF ON OFF OFF
LED_IRQSENABLED Interrupts enabled ON ON OFF OFF
LED_STACKCREATED Idle stack created OFF OFF ON OFF
LED_INIRQ In an interrupt** ON N/C N/C OFF
LED_SIGNAL In a signal handler*** N/C ON N/C OFF
LED_ASSERTION An assertion failed ON ON N/C OFF
LED_PANIC The system has crashed N/C N/C N/C ON
LED_IDLE STM32 is is sleep mode (Optional, not used)
* If LED0, LED1, LED2 are statically on, then NuttX probably failed to boot
and these LEDs will give you some indication of where the failure was
** The normal state is LED2 ON and LED3 faintly glowing. This faint glow
is because of timer interrupt that result in the LED being illuminated
on a small proportion of the time.
*** LED1 may also flicker normally if signals are processed.
SERIAL CONSOLE
==============
Pin Availability
----------------
The EFM32G890F128 support the following options for serial output. NOTE
(1) that not all of these pins are available for use as a serial console,
however. And (2) not all pins made available by the board.
EFM32 PIN GPIO NOTES/CONFLICTS/AVAILABILITY
------- -- ---- ----------------------------------------------
US0_RX #0 PE11 LCD_PE11, LCD_SEG7
US0_RX #1 PE6 LCD_PE6, LCD_COM2
US0_RX #2 PC10 UIF_SLIDER2
US0_TX #0 PE10 LCD_PE10, LCD_SEGG
US0_TX #1 PE7 LCD_PE7, LCD_COM3
US0_TX #2 PC11 UIF_SLIDER3
------- -- ----
US1_RX #0 PC1 UIF_LED1
US1_RX #1 PD1 Not connected on this board
US1_TX #0 PC0 UIF_LED0
US1_TX #1 PD0 Not connected on this board
------- -- ----
US2_RX #0 PC3 UIF_LED3
US2_RX #1 PB4 LCD_PB4, LCD_SEG21
US2_TX #0 PC2 UIF_LED2
US2_TX #1 PB3 LCD_PB3, LCD_SEG20
------- -- ----
U0_RX #0 PF7 LCD_PF7, LCD_SEG25
U0_RX #1 PE1 **AVAILABLE at TP130** (if BC_EN is low, see below)
U0_RX #2 PA4 LCD_PA4, LCD_SEG17
U0_RX #3 PC15 MCUDBG_TDO_SWO
U0_TX #0 PF6 LCD_PF6, LCD_SEG24
U0_TX #1 PE0 **AVAILABLE at TP129** (if BC_EN is low, see below)
U0_TX #2 PA3 LCD_PA3, LCD_SEG16
U0_TX #3 PC14 **AVAILABLE at TP117**
------- -- ----
LEU0_RX #0 PD5 **AVAILABLE at TP123 and EXP port pin 14**
LEU0_RX #1 PB14 CTRLMCU_SPI_MISO
LEU0_RX #2 PE15 LCD_PE15, LCD_SEG11
LEU0_TX #0 PD4 **AVAILABLE at TP122 and EXP port pin 12**
LEU0_TX #1 PB13 CTRLMCU_SPI_SCK
LEU0_TX #2 PE14 LCD_PE14, LCD_SEG10
------- -- ----
LEU1_RX #0 PC7 DEBUG_MCU_SW_ENABLE
LEU1_RX #1 PA6 DEBUG_TDI_IN
LEU1_TX #0 PC6 DEBUG_DH_SW_ENABLE
LEU1_TX #1 PA5 DEBUG_TMS_SWDIO_IN
------- -- ----
Default Serial Console
----------------------
LEUART0 is configured as the default serial console at 2400 8N1
on pins PD5 and PD4. It certainly be possible to go to 4800 baud
and the documentation claims that 9600 baud is possible (although
I am not sure how).
It should also be possible to use UART0 is configured at 115200 8N1
on pins PE0 and PE1. However, my attempts to use USART0 were
unsuccessful -- I see no activity on PE0 and PE1 and have not yet
figured out why that is.
Communication through the Board Controller
------------------------------------------
The control MCU acts as a board controller (BC). There is a UART
connection between the EFM and the BC. The connection is made by
setting the EFM_BC_EN (PD13) line high. The EFM can then use the BSP to
send commands to the BC. When EFM_BC_EN is low, EFM_BC_TX and EFM_BC_RX
can be used by other applications.
USING THE J-LINK GDB SERVER
===========================
1. Star the J-Link GDB server. You should see the start-up configuration
window. SelectL
a. Target device = EFM32G880F128
b. Select Target interface = SWD
2. Press OK. The GDB server should start and the last message in the Log
output should be "Waiting for GDB connection".
3. In a terminal window, start GDB:
arm-none-eabi-gdb
4. Connect to the J-Link GDB server:
(gdb) target remote localhost:2331
5. Load and run nuttx
(gdb) mon halt
(gdb) load nuttx
(gdb) mon reset go
I had to tinker with the setup a few times repeating the same steps above
before things finally began to work. Don't know why.
To debug code already burned into FLASH:
1. Start the GDB server as above.
2. In a terminal window, start GDB:
arm-none-eabi-gdb
3. Connect to the J-Link GDB serer:
(gdb) target remote local host
3. Load the nuttx symbol file, reset, and debug
(gdb) mon halt
(gdb) file nuttx
(gdb) mon reset
(gdb) s
...
CONFIGURATIONS
==============
Each EFM32 Gecko Starter Kit configuration is maintained in a sub-directory
and can be selected as follow:
tools/configure.sh efm32-g8xx-stk:<subdir>
If this is a Windows native build, then configure.bat should be used
instead of configure.sh:
configure.bat efm32-g8xx-stk\<subdir>
Where <subdir> is one of the following:
nsh:
---
Configures the NuttShell (nsh) located at apps/examples/nsh. The
Configuration enables the serial interfaces on LEUART0 at 2400 8N1.
NOTES:
1. This configuration uses the mconf-based configuration tool. To
change this configuration using that tool, you should:
a. Build and install the kconfig-mconf tool. See nuttx/README.txt
see additional README.txt files in the NuttX tools repository.
b. Execute 'make menuconfig' in nuttx/ in order to start the
reconfiguration process.
2. By default, this configuration uses the ARM EABI toolchain
for Windows and builds under Cygwin (or probably MSYS). That
can easily be reconfigured, of course.
CONFIG_HOST_WINDOWS=y : Builds under Windows
CONFIG_WINDOWS_CYGWIN=y : Using Cygwin
CONFIG_ARM_TOOLCHAIN_GNU_EABI=y : GNU EABI toolchain for Windows