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by mikronauts
Wed Aug 16, 2017 3:57 pm
Forum: Python
Topic: HC-SR04 always return 1.0
Replies: 3
Views: 116

Re: HC-SR04 always return 1.0

You can try my article/tutorial: http://www.mikronauts.com/raspberry-pi/gpio-experiments/raspberry-pi-and-hc-sr04-distance-sensor-interfacing-with-c-and-python/ Hi, I have trying to run the example in this tutorial: https://www.raspberrypi.org/learning/physical-computing-with-python/distance/ Howeve...
by mikronauts
Tue Aug 01, 2017 11:17 pm
Forum: Automation, sensing and robotics
Topic: Multiplexing Mabotix Ultrasonic Sensors with Pi
Replies: 5
Views: 297

Re: Multiplexing Mabotix Ultrasonic Sensors with Pi

You are welcome. with 16 analog inputs, easiest way is to use two mcp3008 with ce0 to one ce1 to the other miso mosi sclk to both this assumes you do not need any more spi devices it is also now possible to use other gpio for chip selects with dt-overlay if you want to run the sensors at 5v, run the...
by mikronauts
Tue Aug 01, 2017 5:45 pm
Forum: General discussion
Topic: Raspi hat blocks all the gpio pins
Replies: 32
Views: 1254

Re: Raspi hat blocks all the gpio pins

As alphanumeric said, you can add a prototyping board with a stacking header between the Pi and the Hat.

Adafruit has such a prototyping board.

So does Mikronauts (working on uploading the product pages) basically a 40 pin gpio version of my EZasPi 26 pin boards :-)

Best Regards,

Bill
by mikronauts
Tue Aug 01, 2017 5:43 pm
Forum: Automation, sensing and robotics
Topic: ADXL 345 and duplicate readings
Replies: 7
Views: 348

Re: ADXL 345

Perhaps the sensor has filtering limiting you to 20-30 updates per second?
by mikronauts
Tue Aug 01, 2017 5:41 pm
Forum: Automation, sensing and robotics
Topic: Multiplexing Mabotix Ultrasonic Sensors with Pi
Replies: 5
Views: 297

Re: Multiplexing Mabotix Ultrasonic Sensors with Pi

1) can you post a link to the product page for the exact sensor you have? 2) if it is analog output, you will need an ADC (or two) to connect to your Pi See http://www.mikronauts.com/raspberry-pi/raspberry-pi-analog-to-digital-conversion-experiments-and-howto/ 3) or you can use one ADC, and an exter...
by mikronauts
Mon Jul 31, 2017 7:31 pm
Forum: Troubleshooting
Topic: GPIO pins sensing inputs
Replies: 3
Views: 133

Re: GPIO pins sensing inputs

if your switch connects to ground, you need to pull up the pin to 3v3, say with 10k resistor.

if your switch connects to 3v3, you need to pull down the pin to gnd, say with 10k resistor.
by mikronauts
Thu Jul 27, 2017 4:09 pm
Forum: C/C++
Topic: MCP23S17, Wiringpi or another library
Replies: 14
Views: 631

Re: MCP23S17, Wiringpi or another library

Why on earth would you want to do that?

Save the other CS for another peripheral, you can use up to eight MCP23SXX on one CS.
pinballsp wrote:
Thu Jul 27, 2017 3:31 pm
 
Thanks DougieLawson, but with WiringPi I do not see how may I config two MCP23s17, both with same address but different Chip Select, in same SPI bus.

 
by mikronauts
Mon Jul 24, 2017 8:30 pm
Forum: Beginners
Topic: Using Rotary Encoder to measure the distance
Replies: 1
Views: 93

Re: Using Rotary Encoder to measure the distance

google 'python odometry'
by mikronauts
Wed Jul 19, 2017 3:18 pm
Forum: General discussion
Topic: Powering exteranl 3.3V device
Replies: 5
Views: 309

Re: Powering exteranl 3.3V device

I've read that the original A/B had about 50mA of elbow room left from the on-board 3v3 regulator. Newer Pi's may allow more, however if the 3v3 regulator draws too much, the 5V can be pulled too low, leading to the dreaded lightning symbol indicating low voltage. How much you can draw depends on: -...
by mikronauts
Mon Jul 17, 2017 6:58 pm
Forum: Compute Module
Topic: Expandable baseboard (slot system) for CM3
Replies: 8
Views: 582

Re: Expandable baseboard (slot system) for CM3

Imre, I am probably stating the obvious here... 1) You do realise the CM3's pins do not form a "bus" in computer terms? It would be possible to emulate one, but it would be painfully slow. 2) Multiple CM3's could form a cluster, but you would need to add Ethernet PHY's and an ethernet switch It woul...
by mikronauts
Sun Jul 16, 2017 4:19 pm
Forum: Beginners
Topic: help a noob control 8 motors and a sensor
Replies: 7
Views: 353

Re: help a noob control 8 motors and a sensor

you need to figure out the mass of the objects you want to move before you can find the motors you need
by mikronauts
Wed Jul 12, 2017 5:56 pm
Forum: General discussion
Topic: Password Protect SD Card?
Replies: 20
Views: 1085

Re: Password Protect SD Card?

Google "usb protection dongle"
by mikronauts
Wed Jul 12, 2017 5:31 pm
Forum: General discussion
Topic: Password Protect SD Card?
Replies: 20
Views: 1085

Re: Password Protect SD Card?

Can't be done. Also would not protect against image copying. If you are worried about copying, add an appropriate USB key dongle. Thanks, I would like to password protect the sd card so someone can't plug the sd card into a computer and get the contents but if it is plugged in to a certain sd card i...
by mikronauts
Fri Jul 07, 2017 4:03 pm
Forum: General discussion
Topic: No more WDLabs?
Replies: 21
Views: 1660

Re: No more WDLabs?

Too bad.

I just received my PiDrive 375GB.
W. H. Heydt wrote:I have received an e-mail from WD Labs. The shutdown is not a rumor.
by mikronauts
Fri Jun 30, 2017 4:40 pm
Forum: Raspbian
Topic: PiBakery
Replies: 9
Views: 841

Re: PiBakery

This looks like a nice project! Two requests: 1) Linux support - I don't run MacOS, and I run Windows as little as possible :) 2) Source tarball generation - have Pi bakery generate a shell script that would download all the sources for the Raspbian configuration that it generates, and have the scri...
by mikronauts
Fri Jun 30, 2017 4:31 pm
Forum: General discussion
Topic: Pi Zero now available in multiples !
Replies: 15
Views: 1219

Re: Pi Zero now available in multiples !

The one per customer of the bare unit has NOT been lifted.
mikerr wrote:With the lifting of the 1 per customer limit it now becomes a proper product IMO
by mikronauts
Sat Jun 24, 2017 12:41 am
Forum: Networking and servers
Topic: Running multiple pi's on a tractor
Replies: 26
Views: 1202

Re: Running multiple pi's on a tractor

Why on earth do you need 25 Pi3's? So basically I want to run about 25 raspberry pi 3's on my tractor to monitor some stuff using the camera. Electricity-wise, I'm concerned about the different voltages that may come out of the tractor at different revs. What would be the most suitable way to overco...
by mikronauts
Wed Jun 21, 2017 4:47 pm
Forum: Graphics, sound and multimedia
Topic: Using the pi 3 as a 16+ channel DSP
Replies: 6
Views: 438

Re: Using the pi 3 as a 16+ channel DSP

It depends on what you want to do with all those I2S channels. I'd synchronise the Pi's with just one signal, possibly from a master, and transfer the data over Ethernet or USB, using a host to re-assemble/partition the channels - I would not even try to transfer the data between the Pi's over GPIO ...
by mikronauts
Tue Jun 20, 2017 10:57 pm
Forum: Graphics, sound and multimedia
Topic: Using the pi 3 as a 16+ channel DSP
Replies: 6
Views: 438

Re: Using the pi 3 as a 16+ channel DSP

My friend, I have been doing hard real time I/O for ~30 years, on a lot of different micro controllers. It is a LOT more than a "custom driver". Frankly, I am not sure it is feasible at all, even at the lower clock rates. Simultaneously bit-banging 16 channels of I2S audio (8 in, 8 out) in software ...
by mikronauts
Tue Jun 20, 2017 5:32 pm
Forum: Graphics, sound and multimedia
Topic: Using the pi 3 as a 16+ channel DSP
Replies: 6
Views: 438

Re: Using the pi 3 as a 16+ channel DSP

Good luck. Odds of getting it working in any reasonable amount of time are very low. Not impossible, but with that number of channels: 1) go bare metal 2) dedicate a core to inputs 3) dedicate another core to outputs The issue is jitter free timing. The 25MHz is not something guaranteed for all I/O ...
by mikronauts
Tue Jun 20, 2017 5:26 pm
Forum: Automation, sensing and robotics
Topic: RPi, MCP3008 and Pressure Transmitter
Replies: 2
Views: 228

Re: RPi, MCP3008 and Pressure Transmitter

As Joan said, the Pi's 3v3 is a reasonable voltage reference, however it can fluctuate under load, with the error being the exact 3v3 instantaneous voltage at the time the sample is taken. What kind of accuracy do you need? Even with a perfect 3v3 reference (which does not exist) you can only get 3....
by mikronauts
Wed Jun 14, 2017 4:48 pm
Forum: Automation, sensing and robotics
Topic: CamJamEDUKit 3 Motors go at different speeds
Replies: 6
Views: 395

Re: CamJamEDUKit 3 Motors go at different speeds

I've seen +/- 25% different unloaded motor speeds with the cheap yellow gear motors, between motors from the same kit.

These days I measure the unloaded motor speeds of all motors on a bot and use PWM to get the speeds as close as is feasible.

My last two articles in SERVO talked about this.
by mikronauts
Fri Jun 09, 2017 4:44 pm
Forum: Automation, sensing and robotics
Topic: analog input interfacing
Replies: 15
Views: 732

Re: analog input interfacing

You should get a commission! Btw, the reason (as I am sure you have guessed) that I keep harping on ground differential issues is that I've seen people in the past ignore them (run many sensors of different circuits feeding an ADC on yet another)... and then wonder why they are having problems. I wi...
by mikronauts
Thu Jun 08, 2017 6:07 pm
Forum: Automation, sensing and robotics
Topic: analog input interfacing
Replies: 15
Views: 732

Re: analog input interfacing

Thanks - I like that board even more now! If and only if the 24V (pretty standard in industrial I/O) power supplies ground and the Pi's ground have no common mode issues (ie on the same circuit, grounds tied togeather, or transformer isolated with grounds tied togeather) it should work. Otherwise th...
by mikronauts
Wed Jun 07, 2017 5:00 pm
Forum: Official Foundation Display
Topic: Need to see more content on your 7in Touch display?
Replies: 7
Views: 892

Re: Need to see more content on your 7in Touch display?

Also has aliasing issues when scaling down to the native panel resolution.

I have a cheap Win10 tablet with a 1024x600 display - but MS forces the mode to 1280x800, so everything is scaled & fuzzy.

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