boards:pico - wiki.kewl.org

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Raspberry Pi PICO
- Bootloader
- SDK
- FreeRTOS
- Picotool
- Debugprobe
- OpenOCD
- Examples
- J-Link
- Resources

Raspberry Pi PICO

Dual core Arm Cortex-M0 microcontroller designed to run MicroPython.

There are four varieties of PICO version 1 board produced by RPi. The differences are whether they come pre-installed with header pins and a debug socket and if they have a WiFi adapter on board.

Bootloader

Entry to the bootloader occurs when either the flash is empty or the BOOTSEL button is depressed when plugging in the device.

Mounting the drive will gain access to firmware upload.

mount /dev/sda1 /mnt
cat /mnt/INFO_UF2.TXT

RP2040-B1

UF2 Bootloader v2.0
Model: Raspberry Pi RP2
Board-ID: RPI-RP2

RP2040-B2

UF2 Bootloader v3.0
Model: Raspberry Pi RP2
Board-ID: RPI-RP2

UF2 Bootloader v3.0
Model: Raspberry Pi RP2
Board-ID: RPI-RP2

SDK

Github repository

apt install build-essential git pkg-config libusb-1.0-0-dev cmake

mkdir -p /opt
cd /opt
git clone https://github.com/raspberrypi/pico-sdk
cd pico-sdk
git submodule update --init

setenv PICO_SDK_PATH /opt/pico-sdk

FreeRTOS

Github repository

cd /opt
git clone https://github.com/FreeRTOS/FreeRTOS-Kernel

setenv FREERTOS_KERNEL_PATH /opt/FreeRTOS-Kernel

Picotool

This tool is used to convert ELF binaries into UF2 objects to upload to the PICO. and to inspect running firmware via the bootloader.

Github repository

mkdir -p /opt/src
cd /opt/src
git clone https://github.com/raspberrypi/picotool
cd picotool
git submodule update --init
mkdir build
cd build
cmake ..
make
make install

cp /opt/src/picotool/udev/99-picotool.rules /etc/udev/rules.d
udevadm control --reload-rules
udevadm trigger

Picotool can show flash info when in bootloader mode.

Below are two PICOs which contain no firmware and one other running debugprobe.

picotool info -a
Multiple RP2040 devices in BOOTSEL mode found:

Device at bus 1, address 37:
----------------------------
Program Information
 none

Fixed Pin Information
 none

Build Information
 none

Device Information
 type:      RP2040
 revision:  B2

Device at bus 1, address 40:
----------------------------
Program Information
 none

Fixed Pin Information
 none

Build Information
 none

Device Information
 type:      RP2040
 revision:  B2

Device at bus 1, address 41:
----------------------------
Program Information
 name:          debugprobe
 features:      PROBE UART BAUDRATE 115200
                PROBE UART INTERFACE uart1
                UART stdin / stdout
 binary start:  0x10000000
 binary end:    0x10009f70

Fixed Pin Information
 0:   UART0 TX, UART0 TX
 1:   UART0 RX, UART0 RX
 2:   PROBE SWCLK
 3:   PROBE SWDIO
 4:   PROBE UART TX
 5:   PROBE UART RX
 25:  LED

Build Information
 sdk version:       2.0.0
 pico_board:        pico
 build date:        Aug 23 2024
 build attributes:  Release

Device Information
 type:        RP2040
 revision:    B1
 flash size:  2048K
 flash id:    0xE66038B7135F7437

Reboot firmware on specific device

picotool reboot --bus 1 --address 41

Debugprobe

Debugprobe turns a Pi PICO into a debugger which can then be used to debug another Pi PICO.

Notice: On the Pi Pico revision B1 the probe will disconnect from the USB bus and lock up with using its UART feature. This was tested on a Pi 4B host.

This project was previously known as picoprobe and the difference would appear to be change in protocol from picoprobe to cmsis-dap as the interface when using OpenOCD.

This is cheap alternative to buying a dedicated debugger.

Debug probe depends on GCC-ARM and Picotool to build from source.

Github repository

cd /opt/src/
git clone https://github.com/raspberrypi/debugprobe
cd debugprobe
git submodule update --init

debugprobe

The debugprobe is also a dedicated hardware device which uses a PI PICO.

Build and copy debugprobe.uf2 to the debugprobe device.

cd /opt/src/debugprobe
mkdir debugprobe
cd debugprobe
cmake ..
make

Pi PICO

A regular PI PICO as a debugger has its own firmware.

Build and copy debugprobe_on_pico.uf2 to a Pi PICO device.

cd /opt/src/debugprobe
mkdir debugprobe_on_pico
cd debugprobe_on_pico
cmake -DDEBUG_ON_PICO=1 ..
make

USB

usb 1-1.1: new full-speed USB device number 5 using dwc_otg
usb 1-1.1: New USB device found, idVendor=2e8a, idProduct=000c, bcdDevice= 2.01
usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.1: Product: Debugprobe on Pico (CMSIS-DAP)
usb 1-1.1: Manufacturer: Raspberry Pi
usb 1-1.1: SerialNumber: E66038B7135F7437
cdc_acm 1-1.1:1.1: ttyACM0: USB ACM device
usbcore: registered new interface driver cdc_acm
cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

OpenOCD

Using OpenOCD to debug one PI PICO with another.

Build OpenOCD from source.

Wiring

debubprobe_on_Pico GND           Target Pico GND
debugprobe_on_Pico GP2           Target Pico SWCLK
debugprobe_on_Pico GP3           Target Pico SWDIO
debugprobe_on_Pico GP4/UART1 TX  Target Pico GP1/UART0 RX
debugprobe_on_pico GP5/UART1 RX  Target Pico GP0/UART0 TX

Debug

openocd -f "interface/cmsis-dap.cfg" -f "target/rp2040.cfg" -c "adapter speed 5000"
Open On-Chip Debugger 0.12.0+dev-00683-gac63cd00d (2024-08-24-12:37)
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 : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : Using CMSIS-DAPv2 interface with VID:PID=0x2e8a:0x000c, serial=E66038B7135F7437
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.core0] Examination succeed
Info : [rp2040.core1] Cortex-M0+ r0p1 processor detected
Info : [rp2040.core1] target has 4 breakpoints, 2 watchpoints
Info : [rp2040.core1] Examination succeed
Info : [rp2040.core0] starting gdb server on 3333
Info : Listening on port 3333 for gdb connections

Program

#! /bin/bash

if test $# -ne 1; then
        echo "missing arg"
        exit 1
fi

ELF=$1

openocd -f "interface/cmsis-dap.cfg" -f "target/rp2040.cfg" -c "adapter speed 5000" \
        -c "program $ELF preverify verify reset exit"

Examples

Github repository

cd /opt/src
git clone https://github.com/raspberrypi/pico-examples
cd pico-examples
mkdir build
cd build
cmake ..
make

cd /opt/src/pico-examples/build/blink
openocd -f "interface/cmsis-dap.cfg" -f "target/rp2040.cfg" -c "adapter speed 5000" -c "program blink.elf preverify verify reset exit"
Open On-Chip Debugger 0.12.0-00024-g34afaa939 (2024-08-26-02:18) [https://github.com/STMicroelectronics/OpenOCD]
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
adapter speed: 5000 kHz

Info : Using CMSIS-DAPv2 interface with VID:PID=0x2e8a:0x000c, serial=E66038B7135F7437
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
Info : starting gdb server for rp2040.core1 on 3334
Info : Listening on port 3334 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
**pre-verifying**
Error: checksum mismatch - attempting binary compare
** 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 0x100019ec with 20 bytes (bank write end alignment)
Warn : Adding extra erase range, 0x10001a00 .. 0x1000ffff
** Programming Finished **
** Verify Started **
** Verified OK **
** Resetting Target **
shutdown command invoked

J-Link

Segger J-Link can be use to interact with the PICO via the debug port.

Connect SWCLK, SWDIO and VREF on the target PICO.

CORE 0

echo "exit" | /opt/JLink/JLinkExe -device RP2040_M0_0 -if swd -speed 4000 -autoconnect 1 -nogui 1
SEGGER J-Link Commander V7.82a (Compiled Oct 31 2022 11:25:49)
DLL version V7.82a, compiled Oct 31 2022 11:25:22

Connecting to J-Link via USB...O.K.
Firmware: J-Link EDU Mini V1 compiled Oct 21 2022 11:17:52
Hardware version: V1.00
J-Link uptime (since boot): 0d 00h 09m 41s
S/N: 801011752
License(s): FlashBP, GDB
USB speed mode: Full speed (12 MBit/s)
VTref=3.259V
Device "RP2040_M0_0" selected.


Connecting to target via SWD
ConfigTargetSettings() start
J-Link script: ConfigTargetSettings()
ConfigTargetSettings() end
Found SW-DP with ID 0x0BC12477
DPIDR: 0x0BC12477
CoreSight SoC-400 or earlier
Scanning AP map to find all available APs
AP[1]: Stopped AP scan as end of AP map has been reached
AP[0]: AHB-AP (IDR: 0x04770031)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FF000
CPUID register: 0x410CC601. Implementer code: 0x41 (ARM)
Found Cortex-M0 r0p1, Little endian.
FPUnit: 4 code (BP) slots and 0 literal slots
CoreSight components:
ROMTbl[0] @ E00FF000
[0][0]: E000E000 CID B105E00D PID 000BB008 SCS
[0][1]: E0001000 CID B105E00D PID 000BB00A DWT
[0][2]: E0002000 CID B105E00D PID 000BB00B FPB
Cortex-M0 identified.

CORE 1

echo "exit" | /opt/JLink/JLinkExe -device RP2040_M0_1 -if swd -speed 4000 -autoconnect 1 -nogui 1
SEGGER J-Link Commander V7.82a (Compiled Oct 31 2022 11:25:49)
DLL version V7.82a, compiled Oct 31 2022 11:25:22

Connecting to J-Link via USB...O.K.
Firmware: J-Link EDU Mini V1 compiled Oct 21 2022 11:17:52
Hardware version: V1.00
J-Link uptime (since boot): 0d 00h 09m 48s
S/N: 801011752
License(s): FlashBP, GDB
USB speed mode: Full speed (12 MBit/s)
VTref=3.260V
Device "RP2040_M0_1" selected.


Connecting to target via SWD
ConfigTargetSettings() start
J-Link script: ConfigTargetSettings()
ConfigTargetSettings() end
Found SW-DP with ID 0x0BC12477
DPIDR: 0x0BC12477
CoreSight SoC-400 or earlier
Scanning AP map to find all available APs
AP[1]: Stopped AP scan as end of AP map has been reached
AP[0]: AHB-AP (IDR: 0x04770031)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FF000
CPUID register: 0x410CC601. Implementer code: 0x41 (ARM)
Found Cortex-M0 r0p1, Little endian.
FPUnit: 4 code (BP) slots and 0 literal slots
CoreSight components:
ROMTbl[0] @ E00FF000
[0][0]: E000E000 CID B105E00D PID 000BB008 SCS
[0][1]: E0001000 CID B105E00D PID 000BB00A DWT
[0][2]: E0002000 CID B105E00D PID 000BB00B FPB
Cortex-M0 identified.