Experiments with PocketCHIP

Herein lies rubbish I've written while messing around with the rather fabulous pocketCHIP. Some of it might even work.

In general, I compile stuff on the device itself, mostly because I'm too lazy to set up a cross compiler. To do that, I edit the files on the device over ssh and use gcc to do the compiling.

To setup sshd on the device:

1. Open the terminal app on the device.
2. Update your apt sources: sudo apt-get update
3. Optionally upgrade everything: sudo apt-get upgrade
4. Install the ssh server: sudo apt-get install openssh-server

The server should be installed and running now. In order to connect to it from another computer you have to find out its IP address. The easiest way to do this is with the command: ip addr show wlan0. You'll see something like this:

chip@chip:~/Development/pocketchip-playing$ ip addr show wlan0
4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 7c:c7:09:e0:b3:59 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.104/24 brd 192.168.1.255 scope global dynamic wlan0
       valid_lft 84753sec preferred_lft 84753sec
    inet6 fe80::7ec7:9ff:fee0:b359/64 scope link 
       valid_lft forever preferred_lft forever

The address you want is just after the word inet and before /24. In this case it's 192.168.1.104. Now you can ssh to that address from your main machine. I'm assuming you have MacOS or Linux installed here and have ssh available from the command line:

1. ssh chip@192.168.1.104
2. Enter the default password chip
3. Optionally but highly recommended, change the default password with the passwd command.

If you're using Windows, checkout PuTTY as a good SSH client to use.

Next, install some development tools. From the chip SSH session:

1. sudo apt-get install gcc gdb make
2. Optionally install git if you want to use that for version control: sudo apt-get install git

Finally, you have to decide how you want to edit the source files. The simplest way is to use nano on the device:

1. From the ssh session: nano main.c
2. Enter a simple C program:

   #include <stdio.h>
   
   int main(int argc, char* argv[]) {
       printf("Hello, world!\n");
       return 0;
   }

3. Compile the program: gcc --std=c11 -ggdb main.c -o main
4. Run the compiled program: ./main

You should see a salutatory message displayed. Now you can go and program anything!

When coding on the chip I like to use Sublime Text to edit the source files on my local machine and mount the chip using sshfs. That allows me to treat the chip as a local directory, with me only switching to the terminal to compile and run the program. If you want to be extra fancy, you can setup a utility on the chip such as rerun to watch the source file(s) and then automatically call make when they change. That lets you get an almost scripting like experience for coding on it which is pretty nifty.