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ee52bs
ee52bs
Associate
July 4, 2012
Question

Cannot enable CAN bus

  • July 4, 2012
  • 14 replies
  • 3517 views
Posted on July 04, 2012 at 18:16 

#include ''ll_can.h'' 
#include ''rcc.h'' 
#include ''gpio.h'' 
#include ''nvic.h'' 
#include ''usb.h'' 
int can_init(int mode) 
{ 
rcc_clk_enable(RCC_GPIOB); //enable GPIO port B 
rcc_clk_enable(RCC_AFIO); //enable AFIO clock 
afio_remap(AFIO_REMAP_CAN_1); //remap to PB8 and PB9 
gpio_set_mode(GPIOB, 8, GPIO_INPUT_FLOATING); //set pin modes 
gpio_set_mode(GPIOB, 9, GPIO_AF_OUTPUT_PP); 
(RCC_BASE->APB1ENR) |= 1 << 
RCC_APB1ENR_CANEN
; //enable CAN clock 
(RCC_BASE->APB1RSTR) |= 1 << 
RCC_APB1ENR_CANRST
; //reset CAN peripheral 
return RCC_BASE->APB1ENR; 
//set up of baud rates, mode, filters etc. 
}

Hi, I am trying to setup the CAN bus in loopback mode on an Olimexino STM32 board (using an STM32F103RBT6), but when I print out the binary value of the APB1 enable register I get 100000000000000000000111 - i.e. the USB clock is enabled, and TIM2, 3 and 4 are enabled.I'd be grateful if anyone has any ideas to solve this? #can-bus #olimexino
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14 replies

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ee52bs
ee52bsAuthor
Associate
July 10, 2012
Posted on July 10, 2012 at 18:54

I have managed to get the controller to switch back to normal mode, by playing with the baud rates. I am now working on transmitting data in loopback mode and I have a few more questions :)

>In loopback mode do I need to do anything to the hardware set up on my board such as put a resistor between the CANH and CANL terminals of the CAN transceiver?

>Since the switch from INIT to NORMAL mode works OK does this suggest I have my clocks and baud rate set up correctly or could this still be a problem?

>USB and CAN share the same transmit/ recieve SRAM in the controller I am using (STM32F103RBT6), so it is not possible to use both at the same time. If the USB clock is disabled are there any other sources of interference between the USB and CAN?

Thanks!

emmanuelmigabo2007
emmanuelmigabo2007
Visitor II
October 12, 2012
Posted on October 12, 2012 at 11:15

Hey Clivel!

I am using STM32f103CB microcontroller with my codes attached in this post!I can see something when I change the mode to loop_back mode but doesn't get anything out of the CAN_TX pin when operating in normal mode!I have checked my settings and even compared them with the CAN_settings of examples in the STM firmware!

cAN ANYONE ASSIST PLIZ!

________________

Attachments :

CANbus.c : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtE0&d=%2Fa%2F0X0000000aKT%2FyHAp42kRZ8wPogX2u0YqYs8v5z9s8PRd5Mm96OuYbhM&asPdf=false
Tesla DeLorean
Tesla DeLorean
Guru
October 14, 2012
Posted on October 14, 2012 at 04:24

As I indicated in the other thread, I'm not using CAN on an F1 device

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abelloni
abelloni
Associate
December 15, 2013
Posted on December 15, 2013 at 16:42 

#include ''ll_can.h'' 
#include ''rcc.h'' 
#include ''gpio.h'' 
#include ''nvic.h'' 
#include ''usb.h'' 
int can_init(int mode) 
{ 
rcc_clk_enable(RCC_GPIOB); //enable GPIO port B 
rcc_clk_enable(RCC_AFIO); //enable AFIO clock 
afio_remap(AFIO_REMAP_CAN_1); //remap to PB8 and PB9 
gpio_set_mode(GPIOB, 8, GPIO_INPUT_FLOATING); //set pin modes 
gpio_set_mode(GPIOB, 9, GPIO_AF_OUTPUT_PP); 
(RCC_BASE->APB1ENR) |= 1 << 
RCC_APB1ENR_CANEN
; //enable CAN clock 
(RCC_BASE->APB1RSTR) |= 1 << 
RCC_APB1ENR_CANRST
; //reset CAN peripheral 
return RCC_BASE->APB1ENR; 
//set up of baud rates, mode, filters etc. 
}

Hi, I am trying to setup the CAN bus in loopback mode on an Olimexino STM32 board (using an STM32F103RBT6), but when I print out the binary value of the APB1 enable register I get 100000000000000000000111 - i.e. the USB clock is enabled, and TIM2, 3 and 4 are enabled.I'd be grateful if anyone has any ideas to solve this?
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