forum.heinrichsweikamp.com

I need to make CCR cell reader for OSTC3, are the specs for optical communication protocol available somewhere?

I would use OSTC HUD, but I already have two HUDs (rEvo dreams) and third would be just too much.

I would appreciate it if someone could point me to right direction where to find the specs. Thanks!

Cheers,
Kari Kolehmainen

Hi Kari,

heinrichs weikamp HUD data output:

Hardware details of IR Link:
- data rate is 2400 Baud, 8 Databits, 1 Stopbit, no parity, (2400, N, 8, 1)
- Carrier frequency is 38kHz (To be used with a TSOP34838 IR-Receiver)
- 16bit values are transmitted in little Endian format (LOW:HIGH)

Software:

1. Output from HUD (Frame is updated and send every second):
- Total of 15Bytes (~53ms frame length)

Byte 0: 8bit HUD firmware version number
Byte 1: 8bit Status Byte
Byte 2-3: 16bit Sensor1 voltage (in 100µV steps)
Byte 4-5: 16bit Sensor2 voltage (in 100µV steps)
Byte 6-7: 16bit Sensor3 voltage (in 100µV steps)
Byte 8: 8bit Sensor1 ppO2 (in 0.01bar steps)
Byte 9: 8bit Sensor2 ppO2 (in 0.01bar steps)
Byte 10: 8bit Sensor3 ppO2 (in 0.01bar steps)
Byte 11-12: 16bit HUD Battery voltage in mV
Byte 13-14: 16bit Checksum


Status Byte/
Bit0 = 1 -> HUD connection ok
Bit1 = 1 -> HUD is calibrated
Bit2 = 1 -> HUD Battery is low ( Sensor 1 active
Bit4 = 1 -> Sensor 2 active
Bit5 = 1 -> Sensor 3 active
Bit6 = 1 -> HUD calibrated through external interface (DR5)
Bit7 = 1 -> HUD received (valid) data through RS232 input from DR5. Automatically cleared when command was executed

Great, Thanks a lot!

Cheers,
Kari

One followup question about the checksum. Do I understand it correctly that you take two byte wide values, sum them up and take complement as a checksum as with IP protocol?

As in this way of calculating the checksum:

[pre]
while(len>0) //len = 14 8-bit values
{
Checksum = ((data>16) + Checksum;
}
Checksum = ~Checksum;
[/pre]