How do I use SWDIO and SWCLK as standard GPIO but still allow for re-programming?

[grant]

Posted on December 30, 2014 at 08:51

Hi there

I am planning to use the STM32F030F4 for an application where I have a main interface header that I also want to use to program the micros in production.  I am pin limited on the header so this means I need to ''multiplex'' the use of the SWDIO and SWCLK pins.

What I am looking for is a simple way to figure out when booting as to whether I am hooked up to a programmer/debug unit or not so I can choose whether to map the SWDIO/SWCLK pins to their alternate functions or not.

Thanks and regards

Grant

#serial-wire-debug

[Tesla DeLorean]

Posted on December 30, 2014 at 14:56

So have it delay, or switch mode based on a GPIO or USART input?

Pulling BOOT0 high is going to have the chip run it's internal System Loader, and not your code, so the pins should function normally.

[b_harshan]

Posted on December 31, 2014 at 06:40

Sir,

I am working on Cortex m4 over Serial Wire Debug protocol, with some googling i found '' http://markdingst.blogspot.in/2014/03/programming-internal-sram-over-swd.html '' based on this i am trying to access debug core register i am using STM32f407 as host and STM32f407 as target

the sequence i wrote as following.

Host :

1->sending >50 clocks

2->sending jtag to swd sequence 0xE79E(LSB first)

3->sending >50 clocks

4->sending idcode code packet 1|0|1|0|0|1|0|1   =  0xA5

5->sending 1 clock pulse (Turn around Time) changing the direction waiting for ack

6->collecting 3 bits by sending 3 clock pulses

Target

: ACK Success

Host :

7->after success ack sending 33 clock pulses 32(data)+1(parity)

target :

0x2ba01477

Host :

 

 

8->sending 1 clock pulse turnaround period

9->setting CTRLSTAT register CSYSPWRUPREQ and CDBGPWRUPREQ bits by sending packet 1|0|0|1|0|1|0|1  =  0x95

and data = 0x50000000

target :

(ACK success)

 

Host :

10->reading CTRLSTAT register by sending packet 1|0|1|1|0|0|0|1   =  0xB1

11->after success ack sending 33 clock pulses 32(data)+1(parity)

target :

0xffffffff with parity error i don't understand where might be the error could you please suggest me where might be the error                                                                                             Thanks & Regards