Open RF Prototyping

Quick start

This section assumes that the ECApp firmware has been successfully loaded onto the Pico board. (See Building the firmware for details on building and loading the firmware.)

Connect to the Pico board. On Linux, dmesg should display something like the following to indicate that a new serial device (/dev/ttyACM0 in this case) is available for use:

[179579.216951] usb 2-2.1: new full-speed USB device number 10 using uhci\_hcd
[179579.331685] usb 2-2.1: New USB device found, idVendor=2e8a, idProduct=000a
[179579.331688] usb 2-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[179579.331689] usb 2-2.1: Product: Pico
[179579.331690] usb 2-2.1: Manufacturer: Raspberry Pi
[179579.331691] usb 2-2.1: SerialNumber: E660583883389832
[179579.370931] cdc\_acm 2-2.1:1.0: ttyACM0: USB ACM device

On MacOS running ioreg should show the following:

$ ioreg -p IOUSB
+-o Root  <class IORegistryEntry, id 0x100000100, retain 15>
  +-o AppleUSBXHCI Root Hub Simulation@14000000  <class AppleUSBRootHubDevice, id 0x10000035b, registered, matched, active, busy 0 $
    +-o Bluetooth USB Host Controller@14300000  <class AppleUSBDevice, id 0x10000109f, registered, matched, active, busy 0 (1 ms), $
    +-o Pico@14200000  <class AppleUSBDevice, id 0x10000166c, registered, matched, active, busy 0 (4 ms), retain 15>

Use a serial terminal application to connect to the board (for Linux we use tio, on Windows, putty is a good choice, for MacOS we use either Serial or minicom). Since the connection is USB/RS232 pretty much any baud rate is supported. The other relevant serial line parameters are: 8 bits, 1 stop bit, no parity, no flow control. The terminal mode should be line buffered with standalone linefeed characters interpreted as carriage return/linefeed combinations.

Typing the V command should return firmware version information. Something similar to the following:

V
ECApp USB command processor (Pico v0.9).
Copyright, Dyadic Pty Ltd (2022).
.

Entering nothing at all should return the following:

No cmd.

Pinout

Debug with picoprobe and openocd

• Build picoprobe. Note that this requires that the PiPico SDK is already installed.

  git clone --recurse-submodules https://github.com/raspberrypi/picoprobe.git
  cd picoprobe
  mkdir build
  cd build
  cmake
  make
  

  The resulting picoprobe.uf2 is then copied to the pipico.

• Build openocd. Note that on MacOS this will require installing some prerequisities using either homebrew or macports. For example, using homebrew:

  brew install libtool automake libusb wget pkg-config gcc texinfo
  

  git clone https://github.com/raspberrypi/openocd.git --branch picoprobe --depth=1
  cd openocd
  ./bootstrap
  ./configure --enable-picoprobe --disable-werror
  make -j4
  

• Start openocd. Note that the picoprobe hardware should be wired to the target board as shown. Wiring between Pico A (left) and Pico B (right) configuring Pico A as a debugger. Note that if Pico B is a USB Host then you’d want to hook VBUS up to VBUS so it can provide 5V instead of VSYS to VSYS.

  

  openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -s tcl -c "adapter speed 5000"
  

  Open On-Chip Debugger 0.11.0-g4f2ae61-dirty (2023-06-30-19:24)
  Licensed under GNU GPL v2
  For bug reports, read
          http://openocd.org/doc/doxygen/bugs.html
  Info : auto-selecting first available session transport "swd". To override use 'transport select <transport>'.
  Info : Hardware thread awareness created
  Info : Hardware thread awareness created
  Info : RP2040 Flash Bank Command
  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=E660583883389832
  Info : CMSIS-DAP: SWD  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
  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

  In another terminal session:

  ~/.local/zephyr-sdk-0.16.1/arm-zephyr-eabi/bin/arm-zephyr-eabi-gdb zephyr.elf
  

  GNU gdb (Zephyr SDK 0.16.1) 12.1
  Copyright (C) 2022 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.
  Type "show copying" and "show warranty" for details.
  This GDB was configured as "--host=x86_64-host_apple-darwin --target=arm-zephyr-eabi".
  Type "show configuration" for configuration details.
  For bug reporting instructions, please see:
  <https://github.com/zephyrproject-rtos/sdk-ng/issues>.
  Find the GDB manual and other documentation resources online at:
      <http://www.gnu.org/software/gdb/documentation/>.
  
  For help, type "help".
  Type "apropos word" to search for commands related to "word".
  Reading symbols from zephyr.elf...
  (gdb)

  (gdb) target extended-remote localhost:3333

  Remote debugging using localhost:3333
  warning: multi-threaded target stopped without sending a thread-id, using first non-exited thread
  arch_cpu_idle ()
      at /Users/timm/Documents/Electronics/Designs/ProdGitRepos/software/zephyrproject/zephyr/arch/arm/core/aarch32/cpu_idle.S:127
  127               isb
  (gdb)

In emacs, gdb mode should be customized with the path to the ARM/Zephyr gdb version. If the Zephyr SDK is installed under .local this will be ~/.local/zephyr-sdk-0.16.1/arm-zephyr-eabi/bin/arm-zephyr-eabi-gdb. This needs to be done only once.

Start GDB mode using M-x gdb. In the gud command window connect to the running openocd process and load the target file. Now set a breakpoint in main and run the embedded target:

target extended-remote localhost:3333

Remote debugging using localhost:3333
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.warning: multi-threaded target stopped without sending a thread-id, using first non-exited thread
0x10000c10 in ?? ()

(gdb) file zephyr.elf
Reading symbols from zephyr.elf...

(gdb) b main
Breakpoint 1 at 0x10000448: file /Users/timm/Documents/Electronics/Designs/ProdGitRepos/software/zephyrproject/zephyr/build/zephyr/include/generated/syscalls/device.h, line 55.
Note: automatically using hardware breakpoints for read-only addresses.

(gdb) r
Starting program: /Users/timm/Documents/Electronics/Designs/ProdGitRepos/software/zephyrproject/zephyr/build/zephyr/zephyr.elf
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