Resolve: CH32V003 Once write a sketch, can't write a sketch again

[hidori]

Close #202

In CH32V003, PD1 and SWIO are assigned to the same pin, and whether it behaves as GPIO or SWIO is determined by the setting of the built-in register of muc.

In $/system/CH32V00x/USER/system_ch32v00x.c, PD1 is configured to act as gpio as shown below.

RCC->APB2PCENR |= RCC_AFIOEN;
AFIO->PCFR1 |= (1<<15);

Therefore, once you write a sketch to CH32V003, you will never be able to write a sketch to it again.

When developing using the Arduino IDE, most people will likely write sketches multiple times, so this behavior is unacceptable.

[Copilot]

Pull Request Overview

This PR addresses Issue #202 by removing the configuration of PD1 as a GPIO in several system clock setup functions, thereby preventing the device from locking out subsequent sketch uploads.

• Removed duplicated PD1 GPIO configuration calls in clock initialization functions for 8MHz, 24MHz, and 48MHz modes.
• Ensures that the SWIO functionality is preserved for subsequent sketch programming.

Comments suppressed due to low confidence (1)

system/CH32V00x/USER/system_ch32v00x.c:249

• Consider adding an inline comment explaining the removal of the PD1 GPIO configuration, with reference to Issue CH32V003: Once write a sketch, can't write a sketch again #202, to improve code maintainability.

 */

[maxint-rd]

Hello @hidori - I'm not sure if I understand your issue completely. In all my V003 projects I have been able to flash the chip again and again from the IDE, do some interactive debugging and then flash is many more times without issues. However, the ability to do so may become different after using the PD1 pin. Using the SWIO pin for any other function disables the SWIOO function. I believe this is intended behavior.

In the SOP8 package (CH32V003J4M6) pins have multiple functions and some pins even have multiple GPIO's. This feature allows efficient usage of the limited number of pins. One should know that for instance using Serial (PD5/TX) disables the SWIO pin in that package.

Other packages of the V003 do not have such sharing of the SWIO pin, but one might still want to use PD1 as an extra GPIO..
In my opinion removing the possibility to use PD1 introduces a limitation. Perhaps your PR should add a define to optionally disable PD1. (In my board definition (see PR #200) I've added frequently used peripheral selection as menu options in the IDE. Previously these were defines in some system file.)

NOTE: reusing the SWIO pin doesn't brick the chip. After using features such as serial on the SOP8 chip, one can flash it only once. To restore the SWIO function of the pin for flashing one needs to use the WCH-LinkUtility on the LinkE and use the function Clear all code flash - by power off

(Did you know about this method? This is a known feature that has been mentioned in other issues. See for instance issue #143, #157, #194)
Please let me know if I misunderstood your issue.

For reference see pin usage of the J4M6 package: