Sferalabs Iono Pi Max v2 3+ Lite User Manual page 60

If JP2 is not installed, GPIO41 must be high to enable the connection between Pi's
GPIO43-45 and the MCU.
A two-way jumper, JP1, can be used if you need to feed the SWO serial debug output from
the MCU to the Compute Module. Place the jumper in position 1-2 (factory installed) to
route SWO to GPIO42, or in position 2-3 to route SWO to the Pi's main UART RX line
(GPIO15). In this latter configuration the external serial ports must not receive traffic or be
router to the MCU, not to the Compute Module.
Jumpers JP1 and JP2 are located on the main circuit board. In order to easily access
them, you will need to disassemble the vertical board that hosts the Compute Module.
Follow the same procedure as described to replace the real-time-clock battery.
SWD JUMPERS
One of the tools you could use on Raspberry Pi OS or other Linux distributions to flash
new versions of the firmware to the MCU, or perform in-circuit debugging, is OpenOCD .
6
Install OpenOCD and its dependencies:
$ sudo apt install git autoconf libtool libusb-1.0-0-dev
$ git clone --depth 1 https://git.code.sf.net/p/openocd/code openocd
$ cd openocd
$ ./bootstrap
$ ./configure --enable-sysfsgpio --enable-bcm2835gpio
$ make
$ sudo make install
Modify the following configuration file:
/usr/local/share/openocd/scripts/interface/sysfsgpio-raspberrypi.cfg
leaving only the following content:
adapter driver sysfsgpio
sysfsgpio_swd_nums 44 43
sysfsgpio_srst_num 45
6 http://openocd.org
60 Iono Pi Max User Guide