Espruino on the Pi (with WiringPi)

My 9 year old son is an avid user of the scratch programming language and we are working on a modest weather station together. We have light, humidity and temperature sensors attached to a Raspberry Pi. The Raspberry Pi is headless which really limits his options for programming the thing. Thanks to Google I wound up here and quickly configured the Raspberry Pi to work with the Web IDE.

On my son's laptop running Chrome I installed the IDE. I made the following two configuration adjustments:
Settings->General->Overwrite JavaScript with Graphical Editor->Check the Box (true)
Settings->Communications->Baud Rate->115200

As root (relax, this isn't a mission critical server) I did the following:

cd /root
git clone git://git.drogon.net/wiringPi
git clone https://github.com/espruino/Espruino.git­
cd wiringPi
./build
cd ../Espruino
make

Next I installed the socat program.

apt-get install socat

Then, I determined the TTY device of my serial port

root@weather:~# dmesg | grep tty
[    0.000000] Kernel command line: dma.dmachans=0x7f35 bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2708.boardrev=0x10 bcm2708.serial=0x561ae60d smsc95xx.macaddr=B8:27:EB:1A:E6:0D bcm2708_fb.fbswap=1 bcm2708.disk_led_gpio=47 bcm2708.disk_led_active_low=0 sdhci-bcm2708.emmc_clock_freq=250000000 vc_mem.mem_base=0x1ec00000 vc_mem.mem_size=0x20000000  dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
[    0.001749] console [tty1] enabled
[    0.141194] 20201000.uart: ttyAMA0 at MMIO 0x20201000 (irq = 83, base_baud = 0) is a PL011 rev2

In my case the serial device is 'ttyAMAo'

Next I opened /etc/inittab in an editor and ensured that no programs were using /dev/ttyAMAo. Now that I think of it, you may also need to edit the grub config and remove any serial console parameters passed to the kernel. I leave this as an exercise for the reader.

Finally, I added the following to /etc/inittab

T0:23:respawn:socat SYSTEM:/root/Espruino/espruino FILE:/dev/ttyAMA0,b115200,raw

Next I instructed init to re-read the configuration

init q

The Espruino prompt immediately appeared on the IDE. I switched to the graphical editor and it worked too. And just like that my son can explore physical computing on a Raspberry Pi using Espruino.

Time to visit your store and order some boards. I see lots of little creations in his future.