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by rzusman
Mon Jun 13, 2016 5:47 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Serial Communication Question
Replies: 14
Views: 1961

Re: Serial Communication Question

Generally, you can ignore the handshake line.
It's a holdover from the days when processors were really, really slow. Now, with interrupt-driven I/O, the Pi can keep up with the input data. So, just set the RTS line high, and capture the data as in comes in.
by rzusman
Tue Jun 07, 2016 12:35 am
Forum: General discussion
Topic: Difference between Zigbee Zwave and xbee
Replies: 1
Views: 1190

Re: Difference between Zigbee Zwave and xbee

Zigbee is a mesh network protocol. Xbee is Digi’s implementation of Zigbee with an easy-to-use interface, and long range capability. Zwave is a proprietary mesh network designed for home automation. Zwave and Zigbee are similar, but incompatible. IMHO, Zwave has far greater penetration into home aut...
by rzusman
Mon Jun 06, 2016 7:14 pm
Forum: Advanced users
Topic: RPI as controller
Replies: 2
Views: 858

Re: RPI as controller

Start researching 'lirc'

I think there is a pronto->lirc converter somewhere.
by rzusman
Mon May 30, 2016 5:17 pm
Forum: Automation, sensing and robotics
Topic: Strain gauge/load cell advice needed
Replies: 9
Views: 2594

Re: Sensing/logging weight variations in beehive

Among other things, I design pressure gauges, which have similar issues as scales. First of all, you need to pick a load cell that has the right range for your hive. If you expect your hive to weigh 100 ± 25 lbs, it’s a bad idea to use a 1,000 lb. load cell - the amplifier errors and reduced ADC ran...
by rzusman
Mon May 30, 2016 12:29 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Low Accuracy Readings Using MCP3008/MCP3208 [Solved]
Replies: 8
Views: 4009

Re: Low Accuracy Readings Using MCP3008/MCP3208

I would try bypassing your supplies with 1µF and .01µF capacitors to ground.

Read sections 6.4 and 6.5 here:
http://ww1.microchip.com/downloads/en/D ... 21295C.pdf

I'm not sure why the breadboard in the video works as well as it does, but Analog circuits are difficult that way.
by rzusman
Sun May 29, 2016 11:04 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Low Accuracy Readings Using MCP3008/MCP3208 [Solved]
Replies: 8
Views: 4009

Re: Low Accuracy Readings Using MCP3008/MCP3208

ADCs are extremely sensitive to layout issues.
You will never be able to get the spec’d accuracy using a proto board.

Try a nice PCB with a good ground plane and well-bypassed power traces and see what you get.
by rzusman
Sat May 28, 2016 12:02 am
Forum: Raspbian
Topic: lirc question
Replies: 4
Views: 857

Re: lirc question

Are you using lirc?
If not, just disable it.
by rzusman
Sat May 21, 2016 11:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting More GPIO
Replies: 13
Views: 2202

Re: Connecting More GPIO

Sorry, but that schematic is too confusing for me to follow.

Make sure all your pullups / pulldowns are set correctly.

Test the matrix by setting one row at a time, and then pressing all the buttons to see what columns react (or vice-versa). That will help isolate any construction or wiring issues.
by rzusman
Fri May 20, 2016 2:46 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Maximum SPI Devices
Replies: 15
Views: 5347

Re: Maximum SPI Devices

Fan-out is the term.
It's the number of inputs a single output can drive. For most ICs, it's typically "a handful."
You would also have to worry about signal integrity due to reflections caused by impedance mis-match, but that's not usually a big deal for slow, short-length signaling like SPI.
by rzusman
Mon May 16, 2016 12:10 am
Forum: Troubleshooting
Topic: AM-2302 Accuracy?
Replies: 8
Views: 1904

Re: AM-2302 Accuracy?

RH is possibly the hardest common physical parameter to measure accurately.
I think the best you can hope for is decent repeatability, and just deal with calibrating each sensor.
by rzusman
Sun May 15, 2016 11:58 pm
Forum: Troubleshooting
Topic: UART Issue
Replies: 10
Views: 2264

Re: UART Issue

You probably also need to disable the getty process, too.
Google for it.
by rzusman
Fri May 13, 2016 12:23 am
Forum: Troubleshooting
Topic: Old Pioneer TV
Replies: 6
Views: 1061

Re: Old Pioneer TV

Does your cable have active circuitry in it?
Because, I don't think that HDMI carries anything but digital signals, so there's no way to get RGB from it, unless there is some time of converter embedded in the cable.
by rzusman
Thu May 12, 2016 6:47 pm
Forum: Off topic discussion
Topic: Breakthrough Starshot - Mission: Alpha Centauri in 20 years?
Replies: 40
Views: 6632

Re: Breakthrough Starshot - Mission: Alpha Centauri in 20 ye

We should aim aim the probes at the Monk's planet - they would know how to slow them down!

http://www.e-reading.club/chapter.php/7 ... Space.html
by rzusman
Mon May 09, 2016 3:05 pm
Forum: Off topic discussion
Topic: Breakthrough Starshot - Mission: Alpha Centauri in 20 years?
Replies: 40
Views: 6632

Re: Breakthrough Starshot - Mission: Alpha Centauri in 20 ye

What is the point?
How is a 1g device going to transmit a signal back to Earth?
by rzusman
Mon May 09, 2016 3:02 pm
Forum: Compute Module
Topic: Increase flash memory of compute module
Replies: 8
Views: 2511

Re: Increase flash memory of compute module

Why not use an SD card?
They use SPI, so they typically take only 1 additional GPIO (CS).
by rzusman
Sun May 08, 2016 8:57 pm
Forum: General discussion
Topic: Help for PCB circuit config with Rasberry pi
Replies: 5
Views: 820

Re: Help for PCB circuit config with Rasberry pi

What do you want to do?
by rzusman
Sun May 08, 2016 7:11 pm
Forum: Beginners
Topic: LCD High and Low bits
Replies: 3
Views: 570

Re: LCD High and Low bits

It's redundant.
Take any references to bits 4,5,6,7 out.
by rzusman
Sun May 08, 2016 4:51 pm
Forum: Beginners
Topic: LCD High and Low bits
Replies: 3
Views: 570

Re: LCD High and Low bits

It's inefficient code.
The bits are all set to zero first, then set to 1 one-at-a-time if they need to be.

It would be better to treat all 8 GPIOs as a byte, and set them all at once.
by rzusman
Sun May 08, 2016 2:22 am
Forum: Off topic discussion
Topic: Its NOT Worth IT!!!!!
Replies: 37
Views: 9907

Re: Its NOT Worth IT!!!!!

I’ve LOVE to buy a Mac Pro for $1,500!

As for the OP, just because you’re clueless, that doesn’t mean that everyone else is, too...
by rzusman
Tue Apr 26, 2016 7:10 pm
Forum: Troubleshooting
Topic: GPIO Serial on RPi3
Replies: 3
Views: 591

Re: GPIO Serial on RPi3

On the Pi3, pins 14 and 15 are now uart1, so ttys0 is correct.

Some discussion here:
https://openenergymonitor.org/emon/node/12311

and here:
viewtopic.php?f=44&t=143371
by rzusman
Tue Apr 26, 2016 1:46 am
Forum: Advanced users
Topic: How is 3V GPIO usable?
Replies: 13
Views: 2873

Re: How is 3V GPIO usable?

I was reading that there a millions to billions of transistors in a computer. If they can put that much into a computer with a somewhat reasonable price, can I get transistors at a dirt cheap price? If yes, I could build something that could take the combinations of GPIO pin outputs, and build a ci...
by rzusman
Mon Apr 25, 2016 7:21 pm
Forum: General discussion
Topic: Electronics bases
Replies: 6
Views: 859

Re: Electronics bases

What's an "electronics base?"
by rzusman
Mon Apr 25, 2016 6:20 pm
Forum: Beginners
Topic: Monitor self voltage (ADC)
Replies: 13
Views: 3023

Re: Monitor self voltage (ADC)

My take on this ... the ADC readings of a battery agree with your DVM readings of same, but ADC readings of Pi's rails are 20-50mV lower than DVM readings So 20-50mV are getting lost ... down the ground rail? This is certainly possible - Are you measuring with the ADC and the meter at the exact sam...
by rzusman
Mon Apr 25, 2016 2:31 am
Forum: Beginners
Topic: Monitor self voltage (ADC)
Replies: 13
Views: 3023

Re: Monitor self voltage (ADC)

Average your readings.
The ADC is taking a snapshot of the voltage, which is going to vary as the switching regulator adjusts to changing loads.
by rzusman
Sun Apr 24, 2016 4:30 pm
Forum: Python
Topic: Break error
Replies: 6
Views: 630

Re: Break error

Are you indented correctly?

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