all possible I2C bitrates with runtime changing possible

paparazzi · Nov 24, 2011 · 4a4eb45 · 4a4eb45
1 parent 9f52491
commit 4a4eb45
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Showing 3 changed files with 56 additions and 10 deletions.
diff --git a/conf/modules/i2c_abuse_test.xml b/conf/modules/i2c_abuse_test.xml
@@ -5,7 +5,7 @@
     <file name="i2c_abuse_test.h"/>
   </header>
   <init fun="init_i2c_abuse_test()"/>
-  <periodic fun="periodic_50Hz_i2c_abuse_test()" period="0.02" autorun="TRUE" /> 
+  <periodic fun="periodic_50Hz_i2c_abuse_test()" period="0.02" autorun="TRUE" />
   <event fun="event_i2c_abuse_test()" />
   <makefile>
     <file name="i2c_abuse_test.c"/>

diff --git a/sw/airborne/arch/stm32/mcu_periph/i2c_arch.rewritten.c b/sw/airborne/arch/stm32/mcu_periph/i2c_arch.rewritten.c
@@ -1203,15 +1203,65 @@ void i2c_setbitrate(struct i2c_periph *periph, int bitrate)
   {
     if (periph == &i2c2)
     {
-//      I2C_DeInit(I2C1);
-//      I2C_Cmd(I2C2, DISABLE);
+      int devider;
+      int risetime;
 
+      I2C_TypeDef *regs = (I2C_TypeDef *) i2c2.reg_addr;
+
+      // store (just for fun)
       I2C2_InitStruct.I2C_ClockSpeed = bitrate;
-//      I2C_Cmd(I2C2, ENABLE);
-//      I2C_Init(I2C2, i2c2.init_struct);
+
+/*****************************************************
+	Bitrate:
+
+	-CR2 + CCR + TRISE registers
+	-only change when PE=0
+
+	e.g.
+
+	10kHz:  36MHz + Standard 0x708 + 0x25
+	70kHz:  36MHz + Standard 0x101 +
+	400kHz: 36MHz + Fast 0x1E      + 0xb
+
       // 1) Program peripheral input clock CR2: to get correct timings
       // 2) Configure clock control registers
       // 3) Configure rise time register
+******************************************************/
+
+      if (bitrate < 3000)
+        bitrate = 3000;
+
+      // 36MHz, fast scl: 2counts low 1 count high -> / 3:
+      devider = 12000000UL / bitrate;
+
+      // never allow faster than 600kbps
+      if (devider < 20)
+        devider = 20;
+
+      // no overflow either
+      if (devider >=4095)
+        devider = 4095;
+
+      risetime = 1000000 / (bitrate/1000) / 8 / 28;
+
+      if (risetime < 10)
+        risetime = 10;
+
+      if (risetime >=31)
+        risetime = 31;
+
+
+      regs->CR1 &= ~ I2C_CR1_BIT_PE;
+
+      // 1)
+      regs->CR2 = 0x0324;
+      // 2)
+      regs->CCR = 0x8000 + devider;
+      // 3)
+      regs->TRISE = risetime;
+
+      regs->CR1 |=   I2C_CR1_BIT_PE;
+
     }
 
 #ifdef I2C_DEBUG_LED

diff --git a/sw/airborne/modules/benchmark/i2c_abuse_test.c b/sw/airborne/modules/benchmark/i2c_abuse_test.c
@@ -169,9 +169,6 @@ static void i2c_abuse_send_transaction(uint8_t _init)
 
 void event_i2c_abuse_test(void)
 {
-  static uint8_t bit1 = 0;
-  static uint8_t bit2 = 0;
-
   if (i2c_idle(&i2c2))
   {
     LED_ON(5);	// green = idle
@@ -211,13 +208,12 @@ void event_i2c_abuse_test(void)
 		{
 			      i2c_abuse_test_counter = 1;
 
-			      //i2c_setbitrate(&i2c2, i2c_abuse_test_bitrate);
+			      i2c_setbitrate(&i2c2, i2c_abuse_test_bitrate);
 
 			      i2c_abuse_test_bitrate += 17000;
 			      if (i2c_abuse_test_bitrate > 500000)
 			      {
 				i2c_abuse_test_bitrate -= 500000;
-                                bit1 = 1 - bit1;
 			      }
 			    }
 		}