User:Brendlefly62/Radxa x4 N100 sbc with RP2040/Use the RP2040 Microcontroller/Write a new blink program
Write the program
Replace the contents of pico-examples/blink/blink.c with your own program
user $nano pico-examples/blink/blink.cpico-examples/blink/blink.c#include "pico/stdlib.h"
#define GREEN_LED 28 // GPIO28 (pin 3)
#define YELLOW_LED 29 // GPIO29 (pin 5)
#define RED_LED 4 // GPIO04 (pin 7)
// use pin 9 as GND
int main() {
gpio_init(GREEN_LED);
gpio_init(YELLOW_LED);
gpio_init(RED_LED);
gpio_set_dir(GREEN_LED, GPIO_OUT);
gpio_set_dir(YELLOW_LED, GPIO_OUT);
gpio_set_dir(RED_LED, GPIO_OUT);
while (true) {
gpio_put(GREEN_LED, 1);
sleep_ms(250);
gpio_put(YELLOW_LED, 1);
sleep_ms(250);
gpio_put(RED_LED, 1);
sleep_ms(250);
gpio_put(GREEN_LED, 0);
sleep_ms(250);
gpio_put(YELLOW_LED, 0);
sleep_ms(250);
gpio_put(RED_LED, 0);
sleep_ms(250);
}
}
Now recompile it
user $export PICO_SDK_PATH=/home/joe/pico-sdk/
user $cmake .. && make -j$(nproc)Flash the program to the RP2040
The new program will now be transferred to the RP2040, by putting temporarily making the RP2040's storage accessible as USB storage in the X4/N100's filesystem, and copying the new program to that device. After the copy operation completes, the USB storage device will "disappear" (no longer available to the N100 host system), and the program will begin to run on the RP2040
"reboot" the rp2040 to make it accessible as USB storage
This can be done two ways -- by pressing the "boot-sel" button, or by a executing a script to toggle a couple of internal GPIO pins on the N100 (do not confuse this wtih the RP2040 toggling GPIO pins pysically present at the 40-pin header).
Here's now to use the software method
(if pressing the boot-sel button, skip this section) ensure the host X4/N100 system has libgpiod installed (optionally with USE=python)
root #USE="cxx tools" emerge -av dev-libs/libgpiodNow create a script to toggle internal gpio lines to put the rp2040 in usb-storage mode --
root #nano rp2040_usb.shrp2040_usb.sh#! /bin/bash
sudo gpioset gpiochip0 17=1
sudo gpioset gpiochip0 7=1
sleep 1
sudo gpioset gpiochip0 17=0
sudo gpioset gpiochip0 7=0
Make this file executable and save it to a location in this environment's PATH --
root #chmod a+x rp2040_usb.shroot #mv rp2040_usb.sh /usr/local/sbin/put the rp2040 in usb-storage mode
Press the boot-select button or execute the script above --
user $rp2040_usb.shVerify the rp2040 is now available as a storage device
user $lsblk$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 1 14.6G 0 disk
`-sda1 8:1 1 14.6G 0 part
sdb 8:16 1 128M 0 disk
`-sdb1 8:17 1 128M 0 part ### <=== here it is !
nvme0n1 259:0 0 119.2G 0 disk
|-nvme0n1p1 259:1 0 4M 0 part
|-nvme0n1p2 259:2 0 250M 0 part /efi
|-nvme0n1p3 259:3 0 500M 0 part /boot
`-nvme0n1p4 259:4 0 118.5G 0 part
`-ev014 253:0 0 118.5G 0 crypt
|-vg_x401-root 253:1 0 13.5G 0 lvm /
|-vg_x401-usr 253:2 0 40G 0 lvm /usr
|-vg_x401-var 253:3 0 40G 0 lvm /var
|-vg_x401-swap 253:4 0 6G 0 lvm [SWAP]
|-vg_x401-home 253:5 0 5G 0 lvm /home
|-vg_x401-opt 253:6 0 4G 0 lvm /opt
`-vg_x401-tmp 253:7 0 10G 0 lvm /tmpCopy the program to the rp2040
user $sudo mount /dev/sdb1 /mnt/rp2040/user $sudo cp -v blink/blink.uf2 /mnt/rp2040/'blink/blink.uf2' -> '/mnt/rp2040/blink.uf2'
The rp2040 will now "disappear" from availability on the host system, but don't forget to un-do the above mount action, else the system will track the /dev/sdb1 device as used and the next time this procedure is followed, the rp2040 will be assigned a new device node (e.g. sdc1)..
user $sudo umount /mnt/rp2040Now observe the new program running
See video here
https://youtube.com/shorts/Lbe5EFXIKNs?feature=share