STM32F103 PA15 as GPIO

r2d2 · ‎2012-10-25

Posted on October 25, 2012 at 21:49

Hello,

I�m trying to use PA15 pin as an output on STM32F103CB chip, but with no luck.

Because this pin is shared for JTAG, I must use remapping,

First I enable clocks:

RCC->APB2ENR |= RCC_APB2Periph_TIM1 |

RCC_APB2Periph_AFIO |

RCC_APB2Periph_GPIOA;

Then set up AFIO like this:

uint32_t reg = AFIO->MAPR;

reg &= ~(1<<24 | 1<<26);//JTAG-DP Disabled and SW-DP Enabled

reg |= (1<<25);

AFIO->MAPR = reg;

Then i set up GPIOA

reg = GPIOA->CRH;

reg |= GPIO_CRH_MODE15;//output 50mhz

reg &= ~(GPIO_CRH_CNF15);//gpio push-pull

GPIOA->CRH = reg;

And the damn thing does not work. neither through BSRR/BRR nor ODR

I used the same code on STM32F107RC, and it works.

When i tried on another 103 (STM32F103RB) it also did not work as output

If i do not setup it, the internal pullup works as it should.

Also to mention, other jtag pins PB3 and PB4 works as GPIO as they should.

Any suggestions?

#stm32f103

Tesla DeLorean · ‎2012-10-25

Posted on October 25, 2012 at 22:40

GPIOA->CRH = reg; // perhaps?

STM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\GPIO\JTAG_Remap\main.c

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB |
RCC_APB2Periph_AFIO, ENABLE);
/* Disable the Serial Wire Jtag Debug Port SWJ-DP */
GPIO_PinRemapConfig(GPIO_Remap_SWJ_Disable, ENABLE);
/* Configure PA.13 (JTMS/SWDAT), PA.14 (JTCK/SWCLK) and PA.15 (JTDI) as
output push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure PB.03 (JTDO) and PB.04 (JTRST) as output push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_4;
GPIO_Init(GPIOB, &GPIO_InitStructure);

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

r2d2 · ‎2012-10-25

Posted on October 25, 2012 at 22:50

thanks clive1 for an answer, but this was not the error. here i only made a typo.

the real error was that in initialising UART1, i used someway uint16_t for CR which in result rewrite my previous settings of PA15.

now the PA15 works as it should.

case is closed