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by sidtupper
Fri Dec 20, 2019 7:56 pm
Forum: Automation, sensing and robotics
Topic: GPIO resister ladder in the fart detector project
Replies: 4
Views: 450

Re: GPIO resister ladder in the fart detector project

Epilogue: since I was unsuccessful getting the resistor ladder resistance range to span the gas detector threshold voltages on the analog pin A0, I used the digital pin D0 and adjusted its potentiometer to put the logic transition voltage just a hair above the ambient (fart-free) voltage. The ladder...
by sidtupper
Mon Dec 09, 2019 5:27 am
Forum: Automation, sensing and robotics
Topic: GPIO resister ladder in the fart detector project
Replies: 4
Views: 450

Re: GPIO resister ladder in the fart detector project

The resistance ladder works now but I haven't been able to get the voltage of the MQ-4 A0 pin (connected to GPIO4) to go above the GPIO pin hi-lo change threshold of around 1.8V. It's down around 30mV, so when the calibration routine increases the load resistance, the voltage goes even lower so it n...
by sidtupper
Fri Dec 06, 2019 6:11 pm
Forum: Automation, sensing and robotics
Topic: GPIO resister ladder in the fart detector project
Replies: 4
Views: 450

Re: GPIO resister ladder in the fart detector project

Thanks for replying! It turns out that the fart project resister ladder configuration is right. I had reversed the order (MSB -> LSB) of the resisters because the plot of the DAC resister values as specified in the project looked weird compared to the nice curve of the reversed values. If the resist...
by sidtupper
Fri Dec 06, 2019 4:13 am
Forum: Automation, sensing and robotics
Topic: GPIO resister ladder in the fart detector project
Replies: 4
Views: 450

GPIO resister ladder in the fart detector project

The resister ladder is not working as I expected. I've set up the hardware and software as described in https://projects.raspberrypi.org/en/projects/fart-detector/ , except that I'm using a MQ-4 methane sensor rather than the TGS2600 in the project. http://sidtupper.ca/ladder_schematic.png I'm expec...
by sidtupper
Thu Aug 11, 2016 5:40 pm
Forum: HATs and other add-ons
Topic: HMC5983; getting faulty temperature; what am I doing wrong?
Replies: 3
Views: 1395

Re: HMC5983; getting faulty temperature; what am I doing wro

Henri, I get intermittent io errors using a python hmc5883l driver from i2clibraries to access the hmc5983. from i2clibraries import i2c_hmc5983l hmc5983l = i2c_hmc5983l.i2c_hmc5983l(0) hmc5983l.setDeclination(9,54) hmc5983l.setSingleMode() print(hmc5983l) Is there a patch to update ic2libraries for...
by sidtupper
Tue Apr 17, 2012 9:51 pm
Forum: General discussion
Topic: Power Consumption: Some numbers?
Replies: 8
Views: 2861

Re: Power Consumption: Some numbers?

I hope that soon someone will report power consumption numbers.  I'd like to know what a headless Raspberry Pi B uses idling, ie, no keyboard, mouse, display, desktop.  A few bytes of data come in a USB port every 5 minutes.  1 watt would be very nice for my purposes.
by sidtupper
Sat Feb 11, 2012 9:22 pm
Forum: Other projects
Topic: Weather station. With gprs updates and 12V
Replies: 12
Views: 6104

Re: Weather station. With gprs updates and 12V

<t>then in midwinter you"re potentially looking at a daily mean of 2-3% max energy capture, very possibly less. <br/> <br/> Too true. Last winter my nominal 45w of pv panels barely kept up with the needs of the little atom mini-itx datalogger that burns 12w on and 0.3w hibernating. Since it"s awake ...
by sidtupper
Thu Feb 09, 2012 5:57 am
Forum: Other projects
Topic: Weather station. With gprs updates and 12V
Replies: 12
Views: 6104

Re: Weather station. With gprs updates and 12V

<r>Haffa14 said: <br/> <br/> <br/> Hi.<br/> <br/> When i et my hands on a board my first project is going to be a remote weather station to have at our familys cabin.<br/> <br/> <br/> I've had a weather data collection system in an environment (49°22'10"N 123°28'35"W) like yours for a bit more than ...

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