hpssjellis / spares

Spark.io Remote Serial port

SpaReS: Spark.io Remote Serial port

Connects the serial ports of the Spark Core board to a TCP channel.

Implementations

• The Spark.io firmware can be found in the firmware directory.
• An Android app and a Python client for Unix-like systems can be found in the android and python directory, respectively.

Protocol design

Announcement

The IP address of the device is stored in hexadecimal format in the variable called local_ip and can be queries in the following way.

$ curl "https://api.spark.io/v1/devices/XXX/local_ip/?access_token=YYY"
{
  "cmd": "VarReturn",
  "name": "local_ip",
  "result": "C0A80169",
  "coreInfo": {
	"last_app": "",
	"last_heard": "2014-12-28T10:18:03.802Z",
	"connected": true,
	"deviceID": "XXX"
  }
}
$ python
>>> from binascii import unhexlify
>>> map(ord, unhexlify('C0A80169'))
[192, 168, 1, 105]

Connecting

The default port is 42232 (the meaning of life + 232 for RS-232). The first byte describes which port to use (USB, USART 1/2) along with the baudrate. The available baud rates and bit patterns can be seen below.

MSB   LSB
|       |
...0 ....  USB   (/dev/ttyACMx under Linux, Serial in Core Firmware)
...1 ....  USART (RX/TX pins, Serial1 in Core Firmware)
.... ....
.... 0000     300 bps
.... 0001     600 bps
.... 0010    1200 bps
.... 0011    2400 bps
.... 0100    4800 bps
.... 0101    9600 bps
.... 0110   14400 bps
.... 0111   19200 bps
.... 1000   28800 bps
.... 1001   38400 bps
.... 1010   57600 bps
.... 1011  115200 bps

For example, 9600 bps over USB is 0x05, and since the current versions ignore the three most significant bits, ASCII 0x45 (E) can be used for testing; the same applies to 115200 over USART, with ASCII 0x3b (;).

License

The whole project is available under MIT license, see LICENSE.txt.