From 20f95c72bf21389ac92f354d8d81f5fe87772fc0 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Tue, 26 Jun 2018 18:03:42 +0200
Subject: [PATCH] BMP085 basics

---
 Inc/app.h    |   4 ++
 Makefile     |   1 +
 Src/bmp085.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++
 Src/main.c   |   1 +
 4 files changed, 159 insertions(+)
 create mode 100644 Src/bmp085.c

diff --git a/Inc/app.h b/Inc/app.h
index 1fb9965..b125b58 100644
--- a/Inc/app.h
+++ b/Inc/app.h
@@ -13,3 +13,7 @@ extern byte tx_packet[64];
 extern volatile byte rx_packet_state, tx_packet_state;
 
 void tx_packet_send(void);
+
+// bmp085.c
+
+void bmp_init(void);
diff --git a/Makefile b/Makefile
index 3a43c64..220477d 100644
--- a/Makefile
+++ b/Makefile
@@ -57,6 +57,7 @@ Src/debug.c \
 Src/usb.c \
 Src/usbdev.c \
 Src/display.c \
+Src/bmp085.c \
 /aux/misc/stm/F1-package/Drivers/STM32F1xx_HAL_Driver/Src/stm32f1xx_ll_rcc.c \
 /Src/system_stm32f1xx.c \
 Src/stm32f1xx_it.c \
diff --git a/Src/bmp085.c b/Src/bmp085.c
new file mode 100644
index 0000000..4df07c2
--- /dev/null
+++ b/Src/bmp085.c
@@ -0,0 +1,153 @@
+#include "stm32f1xx.h"
+#include "stm32f1xx_hal.h"
+
+#include "util.h"
+#include "app.h"
+
+static uint bmp_read(uint reg, uint bytes)
+{
+  LL_I2C_GenerateStartCondition(I2C1);
+  while (!LL_I2C_IsActiveFlag_SB(I2C1))
+    ;
+  LL_I2C_TransmitData8(I2C1, 0xee);
+  while (!LL_I2C_IsActiveFlag_ADDR(I2C1))
+    ;
+  LL_I2C_ClearFlag_ADDR(I2C2);
+  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+    ;
+  LL_I2C_TransmitData8(I2C1, reg);
+  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+    ;
+  LL_I2C_GenerateStopCondition(I2C1);
+
+  LL_I2C_GenerateStartCondition(I2C1);
+  while (!LL_I2C_IsActiveFlag_SB(I2C1))
+    ;
+  LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_ACK);
+  LL_I2C_TransmitData8(I2C1, 0xef);
+  while (!LL_I2C_IsActiveFlag_ADDR(I2C1))
+    ;
+  LL_I2C_ClearFlag_ADDR(I2C2);
+
+  uint d = 0;
+  for (uint i=0; i<bytes; i++)
+    {
+      if (i == bytes-1)
+	LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
+      while (!LL_I2C_IsActiveFlag_RXNE(I2C1))
+	;
+      d = (d << 8) | LL_I2C_ReceiveData8(I2C1);
+    }
+
+  LL_I2C_GenerateStopCondition(I2C1);
+  return d;
+}
+
+static uint bmp_start_measure(uint type, uint bytes)
+{
+  LL_I2C_GenerateStartCondition(I2C1);
+  while (!LL_I2C_IsActiveFlag_SB(I2C1))
+    ;
+
+  LL_I2C_TransmitData8(I2C1, 0xee);
+  while (!LL_I2C_IsActiveFlag_ADDR(I2C1))
+    ;
+  LL_I2C_ClearFlag_ADDR(I2C2);
+
+  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+    ;
+  LL_I2C_TransmitData8(I2C1, 0xf4);
+
+  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+    ;
+  LL_I2C_TransmitData8(I2C1, type);
+
+  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+    ;
+  LL_I2C_GenerateStopCondition(I2C1);
+
+  while (!LL_GPIO_IsInputPinSet(BMP_DONE_GPIO_Port, BMP_DONE_Pin))
+    ;
+
+  return bmp_read(0xf6, bytes);
+}
+
+// Formulae from BMP085 specs
+static void bmp_recalc(uint UT, uint UP, uint oss, u16 cc[11], int *tt, int *pp)
+{
+  s16 AC1 = cc[0];
+  s16 AC2 = cc[1];
+  s16 AC3 = cc[2];
+  u16 AC4 = cc[3];
+  u16 AC5 = cc[4];
+  u16 AC6 = cc[5];
+  s16 B1 = cc[6];
+  s16 B2 = cc[7];
+  s16 MB = cc[8];
+  s16 MC = cc[9];
+  s16 MD = cc[10];
+  UP >>= (8-oss);
+
+  int X1 = (UT-AC6)*AC5 / (1<<15);
+  int X2 = MC*(1<<11) / (X1+MD);
+  int B5 = X1 + X2;
+  int T = (B5+8) / (1<<4);
+  *tt = T;
+
+  int B6 = B5 - 4000;
+  X1 = (B2*(B6*B6/(1<<12))) / (1<<11);
+  X2 = AC2 * B6 / (1<<11);
+  int X3 = X1 + X2;
+  int B3 = (((AC1*4 + X3) << oss) + 2) / 4;
+  X1 = AC3 * B6 / (1<<13);
+  X2 = (B1*(B6*B6/(1<<12))) / (1<<16);
+  X3 = ((X1+X2) + 2) / (1<<2);
+  uint B4 = (uint)(AC4 * (X3 + 32768)) / (1U<<15);
+  uint B7 = (uint)(UP-B3) * (uint)(50000>>oss);
+  int p;
+  if (B7 < 0x80000000)
+    p = (B7*2) / B4;
+  else
+    p = B7 / B4 * 2;
+  X1 = (p/(1<<8)) * (p/(1<<8));
+  X1 = (X1*3038) / (1<<16);
+  X2 = (-7357*p) / (1<<16);
+  p = p + (X1 + X2 + 3791) / (1<<4);
+  *pp = p;
+}
+
+static u16 bmp_constants[11];
+
+void bmp_init(void)
+{
+  for (uint i=0; i<11; i++)
+    bmp_constants[i] = bmp_read(0xaa + 2*i, 2);
+}
+
+#if 0
+void run_test(void)
+{
+  for (;;)
+    {
+      debug_puts("Constants:");
+      u16 cc[11];
+      for (uint i=0; i<11; i++)
+	{
+	  cc[i] = bmp_read(0xaa + 2*i, 2);
+	  debug_printf(" %04x", cc[i]);
+	}
+      debug_puts("\r\n");
+
+      uint raw_temp = bmp_measure(0x2e, 2);
+      debug_printf("Raw temperature: %04x\r\n", raw_temp);
+
+      uint oss = 3;	// Over-sampling setting
+      uint raw_press = bmp_measure(0xf4 | (oss<<6), 3);
+      debug_printf("Raw pressure: %06x\r\n", raw_press);
+
+      int temp, press;
+      bmp_recalc(raw_temp, raw_press, oss, cc, &temp, &press);
+      debug_printf("Temperature: %d ddegC\r\n", temp);
+      debug_printf("Pressure: %d Pa\r\n", press);
+    }
+#endif
diff --git a/Src/main.c b/Src/main.c
index e77264b..043fe33 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -125,6 +125,7 @@ int main(void)
   /* USER CODE BEGIN 2 */
   display_init();
   usb_start(&usb);
+  // bmp_init();
 
   LL_TIM_EnableCounter(TIM4);
   LL_TIM_EnableIT_UPDATE(TIM4);
-- 
2.39.2