Raspberry Pi Forums

BAStumm

Is it unusual to pass more than one byte at a time in i2c? I'm not very familiar with using this type of communication. I see many places with this device where more than one byte need passed. To set a gpio pin you have to send the command in hex followed by the data (0 or 1). To read temperature yo...

BAStumm

For the sake of anyone that stumbles across this in the future... The device I'm trying to talk to returns 4 bytes of data. Originally I was trying to make 4 calls to int wiringPiI2CRead (int fd) ; which does not work. What I had to do was use a read() to get the data. I'm still using other wiringPi...

BAStumm

I'm pretty new to this i2c stuff and wondering if wiringPi can achieve what I need for communicating to a mod-tc-mk2 UEXT module. I'm unsure how to send/check ack's, stop/start i2c and things of this nature using wiringPi built in i2c helper functions. Here is the flow I need to acheive (from the de...

BAStumm

more info on my struggles/success here... https://www.olimex.com/forum/index.php? ... 6#msg10636 and here... http://www.raspberrypi.org/forums/viewt ... 89#p489489

BAStumm

Sorry for the late response, I guess I didn't have notifications turned on for this topic. modprobe -r i2c_bcm2708 modprobe i2c_bcm2708 baudrate=32000 Once I executed this on my Pi it just started working (it also works at baudrate 80000 but not 100000). I've tested with current and previous version...

BAStumm

Seems this could also be done using javascript to detect the key presses, wiringPi command line stuff and PHP to call wiringPi via exec() or system() functions. For someone familiar with C code, PHP is pretty similar...

BAStumm

These are not home-brew reflow ovens. I work for an oven manufacturer.

BAStumm

The MOD-TC I use is I2c and I use 6+ of these devices per oven (multi-zone ovens for solder reflow if you are familiar with that). At each heat zone I have a single device that reports back temperature and wattage while performing PID closed loop control of either temperature or wattage (depending o...

BAStumm

Hale's Lager doesn't have the same ring as it would for Ale...

BAStumm

I'm dealing with industrial ovens that operate at temperatures in excess of 300 degrees C (or more than 600F). Cost isn't that high, about $3 per T/C with a 3 meter lead. The mod-tc-mk2 is $15. I'd probably go a different route if I didn't need the temperature rating.

BAStumm

I'm using this: https://www.olimex.com/Products/Modules/Sensors/MOD-TC-MK2-31855/open-source-hardware Accepts a Type K thermocouple, has analog input (attach a current sensor for True RMS wattage feedback) and GPIO for pulsing a solid state relay. This allows for temperature and/or wattage control o...

BAStumm

Code: Select all

modprobe -r i2c_bcm2708
modprobe i2c_bcm2708 baudrate=32000

BAStumm

Try a lower i2c baud rate on the pi.

BAStumm

Did you check both i2c bus? Pics use clock stretching, slow the pi i2c bus

BAStumm

Does the pic show when you run i2cdetect?

BAStumm

I'll tend to agree with Gert. The mechanical and safety part of this project is serious business. Torsion springs would help greatly but they need shielded from hands and such. I would still recommend exploring a system that uses lead screws engineered to prevent back-rotation. I use these kinds at ...

BAStumm

Most garage doors use torsion springs.

BAStumm

As other stated, this is not going to be cheap compared to a raised bed that doesn't raise up. But I am not one to say "impossible". I'd start with a 2 start, 0.200" per rev lead screw (at least 4) along with worm gear 30:1 ratio. This gives you 300:1 mechanical advantage or lift a 30...

BAStumm

I had an issue recently with clockstretching and baudrate. I slowed the i2c baud to 80k (down from 100k) to get things working with a pic processor.

BAStumm

Python isn't the only language people use on the RPi. I code in C and utilize the wiringPi library.

BAStumm

Also, there is a library for mcp23017 in wiringPi. Might be worth checking out the example projects in C. You might find that it's not too hard to learn. Or perhaps those libraries are also ported to python.

BAStumm

I believe the library was ported to python. Not sure if threading is supported or not. You could check it out. Try searching the forums, I've never installed nor used the python version.

BAStumm

I believe this change fixed the bug in mcp3422/wiringPi. With nothing connected it returns 0 as value. With channel 1 shorted to 3v3 I get a value of 4095. This is using my example code above.

BAStumm

Sorry, not a python guy. If it were me I'd use a wiringPi and it's built in threading then interrupt on rising or falling edges. Just a quick thought. I have some code that pulses a stepper motor (in a separate thread than main loop) and it can pulse several thousand times per second.

BAStumm

Now it returns immediately with values of zero.

Code: Select all

pi@raspberrypi:~/wiringPi/examples$ sudo ./adc-pi 
ADC-Pi analogRead Program
mcp3422Setup=0
val=0
val=0
pi@raspberrypi:~/wiringPi/examples$

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