From 2578994e74b9e618a08eeaa15ba9f56ddd0c7af6 Mon Sep 17 00:00:00 2001
From: Karim Keddam <karim.kdm@gmail.com>
Date: Tue, 17 Nov 2015 17:19:11 -0500
Subject: [PATCH 1/2] Fixed a bug with the CRC for the ms58xx sensor

---
 drivers/sensors/ms58xx.c | 53 +++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/drivers/sensors/ms58xx.c b/drivers/sensors/ms58xx.c
index ad5108f6cf..f0fefba5ba 100644
--- a/drivers/sensors/ms58xx.c
+++ b/drivers/sensors/ms58xx.c
@@ -4,6 +4,7 @@
  *
  *   Copyright (C) 2015 Omni Hoverboards Inc. All rights reserved.
  *   Author: Paul Alexander Patience <paul-a.patience@polymtl.ca>
+ *   Updated by: Karim Keddam <karim.keddam@polymtl.ca>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -130,7 +131,7 @@ struct ms58xx_dev_s
  ****************************************************************************/
 /* CRC Calculation */
 
-static uint8_t ms58xx_crc(FAR const uint8_t *src, size_t len);
+static uint8_t ms58xx_crc(FAR uint16_t *src, uint8_t crcIndex);
 
 /* I2C Helpers */
 
@@ -187,29 +188,36 @@ static const struct file_operations g_fops =
  *
  ****************************************************************************/
 
-static uint8_t ms58xx_crc(FAR const uint8_t *src, size_t len)
+static uint8_t ms58xx_crc(FAR uint16_t *src, uint8_t crcIndex)
 {
-  uint16_t crc = 0;
-  size_t   i;
-  int      j;
-
-  for (i = 0; i < len; i++)
+  uint16_t cnt;
+  uint16_t n_rem;
+  uint16_t crc_read;
+  uint8_t n_bit;
+  n_rem = 0x00;
+  crc_read = src[crcIndex];
+  src[crcIndex] = (0xFF00 & (src[7]));
+  for(cnt=0;cnt<16;cnt++)
+  {
+    if(cnt%2==1)
+      n_rem ^= (uint16_t)((src[cnt>>1]) & 0x00FF);
+    else
+      n_rem ^= (uint16_t)(src[cnt>>1] >> 8);
+    for(n_bit=8; n_bit > 0; n_bit--)
     {
-      crc ^= src[i];
-
-      for (j = 0; j < 8; j++)
-        {
-          bool xor = (crc & 0x8000) != 0;
-
-          crc <<= 1;
-          if (xor)
-            {
-              crc ^= 0x3000;
-            }
-        }
+      if(n_rem & (0x8000))
+      {
+         n_rem = (n_rem << 1) ^ 0x3000;
+      }
+      else
+      {
+        n_rem = (n_rem << 1);
+      }
     }
-
-  return (uint8_t)(crc >> 12);
+  }
+  n_rem = (0x000F & (n_rem >> 12));
+  src[crcIndex] = crc_read;
+  return (n_rem ^ 0x00);
 }
 
 /****************************************************************************
@@ -417,9 +425,8 @@ static int ms58xx_readprom(FAR struct ms58xx_dev_s *priv)
 
   crcmask         = (uint16_t)0xf << crcshift;
   crc             = (uint8_t)((prom[crcindex] & crcmask) >> crcshift);
-  prom[crcindex] &= ~crcmask;
 
-  if (crc != ms58xx_crc((uint8_t *)prom, sizeof(prom)))
+  if (crc != ms58xx_crc(prom, crcindex))
     {
       sndbg("crc mismatch\n");
       return -ENODEV;

From 522d8917595ff6b004fc4fb07c618a4f77c9cbd6 Mon Sep 17 00:00:00 2001
From: Karim Keddam <karim.kdm@gmail.com>
Date: Tue, 17 Nov 2015 17:21:46 -0500
Subject: [PATCH 2/2] Fixed a bug with the ms58xx sensor initialization

---
 drivers/sensors/ms58xx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/sensors/ms58xx.c b/drivers/sensors/ms58xx.c
index f0fefba5ba..1a4352acdf 100644
--- a/drivers/sensors/ms58xx.c
+++ b/drivers/sensors/ms58xx.c
@@ -413,6 +413,8 @@ static int ms58xx_readprom(FAR struct ms58xx_dev_s *priv)
         break;
     }
 
+  // We have to wait before the prom is ready is be read
+  up_udelay(10000);
   for (i = 0; i < len; i++)
     {
       ret = ms58xx_readu16(priv, MS58XX_PROM_REG+i*2, prom+i);