Creates /dev/dsc_txt and /dev/dsc_bin device nodes which can be used to read and write from the KeyBus of DSC alarm systems.
To test: cat /dev/dsc_txt
If you see all 1's repeating, you likely have CLK and DATA swapped, or DATA is disconnected and floating high.
Simply insmod dscmod.ko to get started once setting the GPIO pins as below.
The binary (/dev/dsc_bin) dev node just emits length prefixed messages as a byte stream rather than new line terminated text.
dsc-node provides a front-end to communicate with DSC alarm systems.
Tested on Raspberry Pi (2) and pcDuino (sunxi/sun4i). It's recommended that the Linux PREEMPT_RT patches be applied when using single core Raspberry Pis. Should work fine on NextThingCo's C.H.I.P too.
KeyBus runs at 12V, so ensure that a level shifter is used. Any level shifter should work, I've used:
- https://www.sparkfun.com/products/12009
- http://www.aliexpress.com/item/1Pcs-5V-to-3-3V-IIC-I2C-Logic-Level-Converter-Bi-Directional-Module-for-Arduino/32307221398.html
Set the GPIO pins used by modifying the keybus gpio struct, replacing 7 and 8 below with whatever GPIO pins correspond to your connections to the KeyBus.
static struct gpio keybus[] = {
{ 7, GPIOF_IN, "DSC CLK" }, // KeyBus Clock (Yellow)
{ 8, GPIOF_IN, "DSC DATA" }, // KeyBus Data (Green)
};
Example data:
denver@pcDuino:~$ sudo cat /dev/dsc_txt
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1 // 0x05 Status messages
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1
...
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1
00010001 0 10101010 10101010 10101010 10101010 10101010 10101010 10101010 10 // 0x11 Supervision Enquiry
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1
...
00000101 0 10010001 00000001 00010000 11000111 00010000 11000111 00010000 11000111 1
The test.py script parses the above and prints the messages in hex, along with [rcv'd checksum | calculated checksum] - OK if these match, or BAD if they don't.
denver@pcDuino:~/dscmod$ sudo python tools/test.py
['27', '00', '91', '01', '10', 'C7', '01', '91', '00'] [0x91|0x91] - OK
['27', '00', '90', '03', '10', 'C7', '00', '91', '00'] [0x91|0x91] - OK
['E6', '00', '2C', '40', '00', '00', '00', '00', '52', '00'] [0x52|0x52] - OK
['27', '00', '91', '01', '10', 'C7', '01', '91', '00'] [0x91|0x91] - OK
This project was largely based off the great work of the folks at http://www.avrfreaks.net/forum/dsc-keybus-protocol - Particularly the posts by 'mrboard'.
The KeyBus can easily be connected to GPIO pins as below:
