一、目的

        

        在上一篇《Raspberry-Pi-PICO系列--第八篇 高级篇使用SWD接口下载和调试（第一章）》 我们已经介绍了如何准备openocd、如何编译picoprobe、如何进行接线，本篇将继续介绍openocd命令如何使用，如何进行下载调试。

二、准备

        首先准备好两块raspberry_pi_pico开发板，其中一块已经烧写好picoprobe.uf2固件，我们称之为pico A；另外一块我们称之为pico B。

        

三、实战

        SWD接口烧写程序

                1、首先我们将PICO A通过USB烧写picoprobe.uf2固件；然后按照下面的连线将PICO A和PICO B连接起来，两块PICO都各自通过USB供电

                        Pico A GND -> Pico B GND
                        Pico A GP2 -> Pico B SWCLK
                        Pico A GP3 -> Pico B SWDIO

                2、修改pico-examples/blink/blink.c 里面的sleep_ms(250); 都改成sleep_ms(500); (主要是为了验证通过SWD下载的的确是新的固件，确定SWD下载成功)，并且重新编译

                        

$ cd ~/workspace/third/raspberry_pi_pico/pico-examples/
$ rm -rf build
$ mkdir build
$ cd build/
$ cmake -DCMAKE_BUILD_TYPE=Debug ..
$ cd blink/
$ make

                 上述命令-DCMAKE_BUILD_TYPE=Debug是为了编译可调试的固件，主要是为了后面的GDB使用。

                3、烧写PICO B固件blink

$ cd ~/workspace/third/raspberry_pi_pico/openocd/
$ sudo src/openocd -f interface/picoprobe.cfg -f target/rp2040.cfg -s ~/workspace/third/raspberry_pi_pico/openocd/tcl   -c "program /home/$USER/workspace/third/raspberry_pi_pico/pico-examples/build/blink/blink.elf  verify reset exit"
Open On-Chip Debugger 0.11.0-g4f2ae61-dirty (2022-02-20-17:41)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Info : only one transport option; autoselect 'swd'
adapter speed: 5000 kHz

Info : Hardware thread awareness created
Info : Hardware thread awareness created
Info : RP2040 Flash Bank Command
Info : clock speed 5000 kHz
Info : SWD DPIDR 0x0bc12477
Info : SWD DLPIDR 0x00000001
Info : SWD DPIDR 0x0bc12477
Info : SWD DLPIDR 0x10000001
Info : rp2040.core0: hardware has 4 breakpoints, 2 watchpoints
Info : rp2040.core1: hardware has 4 breakpoints, 2 watchpoints
Info : starting gdb server for rp2040.core0 on 3333
Info : Listening on port 3333 for gdb connections
target halted due to debug-request, current mode: Thread 
xPSR: 0xf1000000 pc: 0x000000ee msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0xf1000000 pc: 0x000000ee msp: 0x20041f00
** Programming Started **
Info : RP2040 B0 Flash Probe: 2097152 bytes @10000000, in 512 sectors

target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
Info : Writing 24576 bytes starting at 0x0
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
** Programming Finished **
** Verify Started **
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x00000178 msp: 0x20041f00
** Verified OK **
** Resetting Target **
shutdown command invoked

                

$ sudo src/openocd -f interface/picoprobe.cfg -f target/rp2040.cfg -s ~/workspace/third/raspberry_pi_pico/openocd/tcl   -c "program /home/$USER/workspace/third/raspberry_pi_pico/pico-examples/build/blink/blink.elf  verify reset exit"

                注意当前使用的openocd是我们通过源码编译的版本，编译后的openocd在src目录下，所以我们在openocd源码目录下执行

                -f interface/picoprobe.cfg 告诉openocd使用picoprobe的配置来访问SWD接口

                -f target/rp2040.cfg 告诉openocd我们要访问基于RP2040的芯片的板子

                -s ~/workspace/third/raspberry_pi_pico/openocd/tcl 告诉openocd去~/workspace/third/raspberry_pi_pico/openocd/tcl目录下找上面的两个配置

                -c "program /home/$USER/workspace/third/raspberry_pi_pico/pico-examples/build/blink/blink.elf  verify reset exit"    告诉openocd执行命令，分别为编程（烧写）elf固件，路径必须是绝对路径或者相对路径、验证、复位、退出。

                当看到一下内容时说明执行成功

        SWD调试程序

                1、安装GDB

$ sudo apt install gdb-multiarch

                2、执行openocd命令

                

$ sudo src/openocd -f interface/picoprobe.cfg -f target/rp2040.cfg -s ~/workspace/third/raspberry_pi_pico/openocd/tcl

                屏幕输出一下内容

                

                从图中我们可以看到gdb server在localhost:3333端口上监听

                3、开始调试

                        新开一个terminal，进入到目录~/workspace/third/raspberry_pi_pico/pico-examples/build/blink下并输入gdb命令

$ cd workspace/third/raspberry_pi_pico/pico-examples/build/blink/
$ gdb-multiarch blink.elf

                然后可以看到

        

                4、开启GDB调试需要输入命令

                

target remote localhost:3333

                 

                5、输入load命令加载blink.elf到flash中 

                6、输入一下命令后程序就已经在运行

monitor reset init
continue

                

                 7、设置断点

                

                 8、单步调试命令

                关于GDB的使用细节，感兴趣的同学可以自行google；后续我也会出GDB调试详细教程。                     

至此，我们就完成了通过SWD下载、复位、调试程序的过程。

下一篇将介绍如何通过Visual Studio Code来进行开发以及调试。