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CAN baud rate selection for STM32.

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This commit is contained in:
James Snyder 2009-06-29 19:29:16 +00:00
parent cff5626558
commit 67f782f057
1 changed files with 32 additions and 6 deletions
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38
src/platform/stm32/platform.c
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@ -316,11 +316,26 @@ void cans_init( void )
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN, ENABLE);
}
/* BS1 BS2 SJW Pre
1M: 5 3 1 4
500k: 7 4 1 6
250k: 9 8 1 8
125k: 9 8 1 16
100k: 9 8 1 20 */
#define CAN_BAUD_COUNT 5
static const u8 can_baud_bs1[] = { CAN_BS1_9tq, CAN_BS1_9tq, CAN_BS1_9tq, CAN_BS1_7tq, CAN_BS1_5tq };
static const u8 can_baud_bs2[] = { CAN_BS1_8tq, CAN_BS1_8tq, CAN_BS1_8tq, CAN_BS1_4tq, CAN_BS1_3tq };
static const u8 can_baud_sjw[] = { CAN_SJW_1tq, CAN_SJW_1tq, CAN_SJW_1tq, CAN_SJW_1tq, CAN_SJW_1tq };
static const u8 can_baud_pre[] = { 20, 16, 8, 6, 4 };
static const u32 can_baud_rate[] = { 100000, 125000, 250000, 500000, 1000000 };
u32 platform_can_setup( unsigned id, u32 clock )
{
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
int cbaudidx = -1;
// Configure IO Pins -- This is for STM32F103RE
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
@ -334,6 +349,17 @@ u32 platform_can_setup( unsigned id, u32 clock )
GPIO_PinRemapConfig( GPIO_Remap1_CAN, ENABLE );
// Select baud rate up to requested rate, except for below min, where min is selected
if ( clock >= can_baud_rate[ CAN_BAUD_COUNT - 1 ] ) // round down to peak rate if >= peak rate
cbaudidx = CAN_BAUD_COUNT - 1;
else
{
for( cbaudidx = 0; cbaudidx < CAN_BAUD_COUNT - 1; cbaudidx ++ )
{
if( clock < can_baud_rate[ cbaudidx + 1 ] ) // take current idx if next is too large
break;
}
}
/* Deinitialize CAN Peripheral */
CAN_DeInit();
@ -347,11 +373,11 @@ u32 platform_can_setup( unsigned id, u32 clock )
CAN_InitStructure.CAN_RFLM=DISABLE;
CAN_InitStructure.CAN_TXFP=DISABLE;
CAN_InitStructure.CAN_Mode=CAN_Mode_Normal;
CAN_InitStructure.CAN_SJW=CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1=CAN_BS1_3tq;
CAN_InitStructure.CAN_BS2=CAN_BS2_5tq;
CAN_InitStructure.CAN_Prescaler=4; // @@@ This should actually be configured!
CAN_Init(&CAN_InitStructure);
CAN_InitStructure.CAN_SJW=can_baud_sjw[ cbaudidx ];
CAN_InitStructure.CAN_BS1=can_baud_bs1[ cbaudidx ];
CAN_InitStructure.CAN_BS2=can_baud_bs2[ cbaudidx ];
CAN_InitStructure.CAN_Prescaler=can_baud_pre[ cbaudidx ];
CAN_Init( &CAN_InitStructure );
/* CAN filter init */
CAN_FilterInitStructure.CAN_FilterNumber=0;
@ -365,7 +391,7 @@ u32 platform_can_setup( unsigned id, u32 clock )
CAN_FilterInitStructure.CAN_FilterActivation=ENABLE;
CAN_FilterInit(&CAN_FilterInitStructure);
return clock;
return can_baud_rate[ cbaudidx ];
}
/*
u32 platform_can_op( unsigned id, int op, u32 data )