OpenWRT-RPI build setup

Step 1 : Clone the openwrt source tree

$ mkdir openwrt_src $ cd openwrt_src $ git clone https://github.com/openwrt/openwrt.git

Step 2: Get the latest updates for the feeds

$ ./scripts/feeds update -a $ ./scripts/feeds install -a

Step 3: Do make menuconfig

$ make menuconfig

Step 4: Select target System as Broadcom BCM27XX for RPI Model 4B

Step 5: Select hostapd and wpa-supplicant

Step 6: Save the configuration in .config file

Step 7 : Build the image

$ make make[1] world make[2] target/compile make[3] -C target/linux compile make[2] buildinfo make[3] diffconfig buildversion feedsversion make[2] package/cleanup make[2] package/compile . . make[2] target/install make[3] -C target/linux install make[2] package/index make[2] json_overview_image_info make[2] checksum

Step 8 : After build completion image will be stored in bin/targets

test@test:bin$ tree -d . |-- packages | `-- aarch64_cortex-a72 | |-- base | |-- luci | |-- packages | |-- routing | `-- telephony `-- targets |-- ath79 | `-- generic `-- bcm27xx `-- bcm2711 `-- packages 13 directories test@test:bin$ test@test:bin$ ls -la targets/bcm27xx/bcm2711/ total 52732 drwxr-xr-x 3 test test 4096 Nov 28 01:11 . drwxr-xr-x 3 test test 4096 Nov 27 22:39 .. -rw-r--r-- 1 test test 992 Nov 28 08:31 config.buildinfo -rw-r--r-- 1 test test 263 Nov 28 08:31 feeds.buildinfo -rw-r--r-- 1 test test 14105707 Nov 28 08:33 openwrt-bcm27xx-bcm2711-rpi-4-ext4-factory.img.gz -rw-r--r-- 1 test test 14106554 Nov 28 08:33 openwrt-bcm27xx-bcm2711-rpi-4-ext4-sysupgrade.img.gz -rw-r--r-- 1 test test 3206 Nov 28 08:33 openwrt-bcm27xx-bcm2711-rpi-4.manifest -rw-r--r-- 1 test test 12869698 Nov 28 08:33 openwrt-bcm27xx-bcm2711-rpi-4-squashfs-factory.img.gz -rw-r--r-- 1 test test 12870545 Nov 28 08:33 openwrt-bcm27xx-bcm2711-rpi-4-squashfs-sysupgrade.img.gz drwxr-xr-x 2 test test 4096 Nov 28 08:33 packages -rw-r--r-- 1 test test 1784 Nov 28 08:33 profiles.json -rw-r--r-- 1 test test 912 Nov 28 08:33 sha256sums -rw-r--r-- 1 test test 18 Nov 28 08:31 version.buildinfo test@test:bin$

Step 9 : Flash using dd tool

1. Use lsblk command to see what the device connected to the system

2. If your computer has a slot for SD cards, insert the card. If not, insert the card into an SD card reader, then connect the reader to your computer.

3. Use lsblk command again, the new device that has appeared is your SD card

4. Use below command to flash the SD card, if is the image which is to be flashed and of is the SD card where the image is to be flashed.

Step 10 : Flash using Balena Etcher tool

1. If your computer has a slot for SD cards, insert the card. If not, insert the card into an SD card reader, then connect the reader to your computer.

2. Download the Balena Etcher tool from the link https://www.balena.io/etcher/ and extract it and run the binary.

3. Extract the zip and run the binary

$ ls
balena-etcher-electron-1.7.0-linux-x64.zip

$ unzip balena-etcher-electron-1.7.0-linux-x64.zip 
Archive:  balena-etcher-electron-1.7.0-linux-x64.zip
  inflating: balenaEtcher-1.7.0-x64.AppImage  

$ ls
balenaEtcher-1.7.0-x64.AppImage  balena-etcher-electron-1.7.0-linux-x64.zip
test@test:dev_tools$ ./balenaEtcher-1.7.0-x64.AppImage 

4. It will launch “Balena Etcher” GUI, select the image and the SD card and click on flash button

Step 11 : Access the RPI using UART cable. See the pin diagram from RPI board below

1. Connect Black cable of UART cable (GND) to pin 6 of RPI

2. Connect White cable of UART cable (RX of UART) to pin 8 of RPI

3. Connect Green cable of UART cable (TX of UART) to pin 10 of RPI

Step 12: Run minicom to access RPI board

$ sudo minicom -D /dev/ttyUSB0 -b 115200