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by edwardsnick
Sun Oct 16, 2016 9:24 pm
Forum: Python
Topic: Need help with Python Library T6713 CO2 Sensor - I2C
Replies: 4
Views: 1363

Re: Need help with Python Library T6713 CO2 Sensor - I2C

could; but want to avoid installing / running extra processes if possible. They working fine at 50kHz, reading the datasheet of the IR sensor it's minimum is 10kHz so 15kHz will probably work fine too
by edwardsnick
Sun Oct 16, 2016 8:41 pm
Forum: Python
Topic: Need help with Python Library T6713 CO2 Sensor - I2C
Replies: 4
Views: 1363

Re: Need help with Python Library T6713 CO2 Sensor - I2C

Just realized the new code also needs the slow bus speed to work, looks like the ACK is too long and messes with the rest of the conversation, the RPI should delay the conversation but I believe this is a known bug. my trouble is it's messing with my IR sensor which doesn't like the slow bus, going ...
by edwardsnick
Sun Oct 16, 2016 8:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: reading MLX90614 IR sensor
Replies: 35
Views: 23806

Re: reading MLX90614 IR sensor

mmm seems the MLX doesn't like slow bus speeds, I had it slowed to 10khz for a CO2 sensor which wasn't playing nice with the raspberry pi, 100khz works well. Hopefully I can find a happy medium but annoying that the sensor is not working at slow speeds. I prefer slow speeds for reliability, no rush ...
by edwardsnick
Sun Oct 16, 2016 4:16 am
Forum: Python
Topic: Need help with Python Library T6713 CO2 Sensor - I2C
Replies: 4
Views: 1363

Re: Need help with Python Library T6713 CO2 Sensor - I2C

I struggled with this one too as the typical smbus python library won't work with this chip. It uses Modbus protocol over the I2C. I managed to get it to work using the pigpio library but it was a mess and only worked when I slowed down the baudrate due to a delayed clock tick which the raspberry pi...
by edwardsnick
Sat Oct 15, 2016 8:20 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: reading MLX90614 IR sensor
Replies: 35
Views: 23806

Re: reading MLX90614 IR sensor

ok so I attached an oscilloscope and found the problem but no idea why, could be a faulty chip I suppose: Start - Slave address - Write - Ack - Command - Ack - Repeated Start - Slave Address - Read - Ack - Data..... But I get: Start - Slave address - Write - Ack - Command - Ack - Repeated Start - Sl...
by edwardsnick
Sat Oct 15, 2016 1:52 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: reading MLX90614 IR sensor
Replies: 35
Views: 23806

Re: reading MLX90614 IR sensor

weiqing121, I tried your code but I get (I changed the reading to print in binary): pi@raspberrypi ~ $ ./tmpMLX.py ('temp: ', '0b1111111111111111', 1037.5500000000002) ('temp: ', '0b11100000111', -237.16999999999996) ('temp: ', '0b1111111100000111', 1032.5900000000001) ('temp: ', '0b11100000111', -2...
by edwardsnick
Thu Oct 13, 2016 1:53 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Need help with HTU21D Humidity Sensor (for RPi outreach)
Replies: 18
Views: 11492

Re: Need help with HTU21D Humidity Sensor (for RPi outreach)

WOW, what is going on here? I've been miserably trying to use the SMBUS library to interface a CO2 sensor which was never going to work then resorted to installing the PIGPIO library and having to slow the clock speed right down as it wouldn't pause to a delayed clock cycle - a terrible mess althoug...
by edwardsnick
Sat Sep 19, 2015 12:22 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C Modbus
Replies: 1
Views: 1031

I2C Modbus

I want to use this CO2 sensor in a project: http://www.ge-mcs.com/download/co2-flow/T6700_Series_CO2_ensor_Module_Application_Note.pdf The sensor uses I2C communications but the application note says: "The I2C implementation does not use the Serial Line protocol. The sensor does use the Modbus proto...

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