Pico Debugger can upload code once but not twice (when touching sysclk)

Question

I've been playing around with the new Pico Debugger, and it is very nice. I have been running into some issues when using an external GPIO clock as the debugger does not seem able to detect the CPU's after the clock has been changed.

I believe that I have created a minimal(ish) example which can be uploaded once but not twice using the debugger. UART is used with the pico debugger, and the PWM generation from the pico-examples is used to create a 4-cycle wave which allows for verification that the clock has changed frequency.

#include <stdio.h>
#include <string.h>
#include "hardware/pll.h"
#include "hardware/clocks.h"
#include "hardware/structs/pll.h"
#include "hardware/structs/clocks.h"
#include "hardware/pwm.h"
void setup_debug() {
    const uint32_t BAUD_RATE = 115200;
    const uint32_t UART_TX_PIN = 16;
    const uint32_t UART_RX_PIN = 17;
    stdio_uart_init_full(uart0, BAUD_RATE, UART_TX_PIN, UART_RX_PIN);
    printf("\n-------------\n");
    printf("PROGRAM START\n");
    printf("UART0... OK\n");
}
void switch_pico_to_external_clock() {
    printf("Configuring pico clock...");
    clock_configure_gpin(clk_sys, 22, 2000 * KHZ, 2000 * KHZ);
    // Re init uart now that clk_peri has changed
    stdio_init_all();
    printf("ok\n");
}
void start_PWM() {
    // Allocate GPIO 0 and 1 to PWM
    gpio_set_function(0, GPIO_FUNC_PWM);
    gpio_set_function(1, GPIO_FUNC_PWM);
// Find out which PWM slice is connected to GPIO 0 (it's slice 0)
uint slice_num = pwm_gpio_to_slice_num(0);

// Set period of 4 cycles (0 to 3 inclusive)
pwm_set_wrap(slice_num, 3);
// Set channel A output high for one cycle before dropping
pwm_set_chan_level(slice_num, PWM_CHAN_A, 1);
// Set initial B output high for three cycles before dropping
pwm_set_chan_level(slice_num, PWM_CHAN_B, 3);
// Set the PWM running
pwm_set_enabled(slice_num, true);

}
int main() {
    stdio_init_all();
    setup_debug();
    switch_pico_to_external_clock();
    printf("Program done SPINNING...\n");
    start_PWM();
    while (1) {
        sleep_ms(1000);
        printf("Spin...");
    };
}

Running the openOCD command:

openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -c "adapter speed 5000" -c "program src/main.elf verify reset exit"

Fails with

Open On-Chip Debugger 0.12.0-g4257276 (2023-01-27-10:19)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Info : Hardware thread awareness created
Info : Hardware thread awareness created
adapter speed: 5000 kHz
Info : Using CMSIS-DAPv2 interface with VID:PID=0x2e8a:0x000c, serial=E6616407E32D4229
Info : CMSIS-DAP: SWD supported
Info : CMSIS-DAP: Atomic commands supported
Info : CMSIS-DAP: Test domain timer supported
Info : CMSIS-DAP: FW Version = 2.0.0
Info : CMSIS-DAP: Interface Initialised (SWD)
Info : SWCLK/TCK = 0 SWDIO/TMS = 0 TDI = 0 TDO = 0 nTRST = 0 nRESET = 0
Info : CMSIS-DAP: Interface ready
Info : clock speed 5000 kHz
Info : SWD DPIDR 0x0bc12477, DLPIDR 0x00000001
Info : SWD DPIDR 0x0bc12477, DLPIDR 0x10000001
Info : [rp2040.core0] Cortex-M0+ r0p1 processor detected
Info : [rp2040.core0] target has 4 breakpoints, 2 watchpoints
Info : [rp2040.core1] Cortex-M0+ r0p1 processor detected
Info : [rp2040.core1] target has 4 breakpoints, 2 watchpoints
Info : starting gdb server for rp2040.core0 on 3333
Info : Listening on port 3333 for gdb connections
[rp2040.core0] halted due to debug-request, current mode: Thread
xPSR: 0xf1000000 pc: 0x000000ea msp: 0x20041f00
[rp2040.core1] halted due to debug-request, current mode: Thread
xPSR: 0xf1000000 pc: 0x000000ea msp: 0x20041f00
** Programming Started **
Info : Found flash device 'win w25q16jv' (ID 0x001540ef)
Info : RP2040 B0 Flash Probe: 2097152 bytes @0x10000000, in 32 sectors
Info : Padding image section 1 at 0x10005178 with 136 bytes (bank write end alignment)
Warn : Adding extra erase range, 0x10005200 .. 0x1000ffff
** Programming Finished **
** Verify Started **
** Verified OK **
** Resetting Target **
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: Failed to select multidrop rp2040.dap1
Error: Failed to connect multidrop rp2040.dap1
Warn : Connecting DP: stalled AP operation, issuing ABORT
Error: [rp2040.core1] DP initialisation failed
in procedure 'program'

The microcontroller then needs to be reprogrammed by entering the USB bootloader.

I can remove the reset from the openOCD command and it exits with code 0, but I would like to be able to reset the MCU using the debugger.

Would anyone be able to point me in the right direction?

Pico Debugger can upload code once but not twice (when touching sysclk)

0 Answers0