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by mikronauts
Thu Apr 20, 2017 5:10 pm
Forum: Beginners
Topic: Connecting multiple sensors to a PI3
Replies: 4
Views: 2065

Re: Connecting multiple sensors to a PI3

You may find my article helpful: http://www.mikronauts.com/raspberry-pi/gpio-experiments/raspberry-pi-and-hc-sr04-distance-sensor-interfacing-with-c-and-python/ Hello, i'm new to Raspberry PI and i just bought all my sensors that i want. HC-SR04: http://www.ebay.com/itm/262356608628?_trksid=p2057872...
by mikronauts
Wed Apr 19, 2017 6:05 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

I think I covered a lot of this in one of my SERVO articles last year (See "Serving Raspberry Pi", starting in Jan.2016), however more HOWTO's always help. FYI, I've learned to order at least two of any new driver/module I intend to try, precisely due to occasional dead module (either dead on arriva...
by mikronauts
Wed Apr 19, 2017 5:54 pm
Forum: Advanced users
Topic: Massively slow file writes
Replies: 18
Views: 4486

Re: Massively slow file writes

Then change your logging system to only write to a single file on the SD card every 4k (or better 16k) and use a larger SD card so the wear leveling will perform better.

The 30sec spikes you are observing are likely due to Linux updating meta data for the file system on the card.
by mikronauts
Wed Apr 19, 2017 5:49 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

I've used L298N boards a lot before, heck I even designed a robot controller with one in the past. The important to remember things are: - check it without connecting it to a controller by -- connecting the motor voltage (24V in your case) -- make sure you are getting 5V on its voltage regulator out...
by mikronauts
Wed Apr 19, 2017 5:43 pm
Forum: Automation, sensing and robotics
Topic: New to GPIO
Replies: 8
Views: 1532

Re: New to GPIO

Sorry, I don't see how that board supports 5V as there are no visible voltage dividers or other form of level shifting circuitry. Do NOT try to use it on a Pi before trying it stand-alone: - connect 5V to the board (say on Pi's 5V pin) - connect 5V to one of the input screw terminals on it - measure...
by mikronauts
Wed Apr 19, 2017 5:01 pm
Forum: Advanced users
Topic: Massively slow file writes
Replies: 18
Views: 4486

Re: Massively slow file writes

I think you should use a small laptop drive with a USB adapter.

There is an inexpensive WD Pi Drive that would work well for you - it would use more power, but I think it would even out a lot of the write delays.
by mikronauts
Wed Apr 19, 2017 4:36 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

It means that the L298N chip is almost guaranteed to be fried - see the data sheet: https://www.sparkfun.com/datasheets/Robotics/L298_H_Bridge.pdf The logic supply to the L298N is max 7V, so feeding it 24V probably let the magic smoke escape. You could replace the voltage regulator and L298, but if ...
by mikronauts
Wed Apr 19, 2017 4:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: MCP3008 (T-DIS)
Replies: 5
Views: 820

Re: MCP3008 (T-DIS)

Note: if you are running the MCP3008 at 5V, you have to divide DOUT down to 3.3v before connecting it to MISO on the Pi. Hi there, This is an ADC related question. And since the MCP3008 appears to be often used, maybe somebody here can help... I can't see from the data sheet how the DOUT pin needs t...
by mikronauts
Wed Apr 19, 2017 4:13 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

It sounds like the voltage regulator (U2) is fried shorting Vin to its output, it may have come shorted from the factory. You should be able to replace that voltage regulator fairly easily. Before soldering a replacement, make sure that there is no short between Vin and Vout pins on the regulator. Y...
by mikronauts
Sun Apr 16, 2017 6:33 pm
Forum: HATs and other add-ons
Topic: B+HAT EEPROM
Replies: 7
Views: 3942

Re: B+HAT EEPROM

Sorry, I did not catch that you wanted to emulate the eeprom.

In general, as long as you can emulate the i2c 100% it should work.

There is some danger that if the firmware in the Pi changes, the i2c emulation may need to change.
franekz wrote:It is a general question. Not about any particular one.
by mikronauts
Sun Apr 16, 2017 6:09 pm
Forum: HATs and other add-ons
Topic: B+HAT EEPROM
Replies: 7
Views: 3942

Re: B+HAT EEPROM

Which hat?

Post a link to the hat you are asking about.
franekz wrote:Hi. I have a quite simple question. Does the hat have EEPROM IC or it is enough to emulate EEPROM by by the HATs uC? It has exactly the same functionality.
by mikronauts
Thu Apr 13, 2017 11:30 pm
Forum: Beginners
Topic: Low voltage in gpio pin output
Replies: 2
Views: 1491

Re: Low voltage in gpio pin output

Pi GPIO pins can supply approx. 5mA @ 3v3, the Pi 3v3 rail can supply more. If the relay needs more than 5mA, it will pull the GPIO pin voltage low (and possibly damage the pin) Normally one looks at the data sheet of the relay to determine what coil voltage and current it needs before hooking it up...
by mikronauts
Thu Apr 13, 2017 4:23 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Raspberry Pi Data Acquisition & SPI Multiplexing (howto)
Replies: 8
Views: 4009

Re: Raspberry Pi Data Acquisition & SPI Multiplexing (howto)

Thank you for your kind words :) and of course, you are most welcome! The current kernel supports using other GPIO as chip selects, so the 74HC138N demultiplexer can potentially be eliminated if you have enough spare GPIO for additional chip selects. What a fantastic 'How To'! Thank you very much fo...
by mikronauts
Thu Apr 13, 2017 12:03 am
Forum: Troubleshooting
Topic: Hardening SD card against power failure?
Replies: 3
Views: 973

Re: Hardening SD card against power failure?

You are most welcome. Sorry, no experience with those HAT's. Some USB powerbanks also allow powering devices while being charged, but they may reboot the Pi on power loss / power return - you will have to test the ones that are available to you. Many thanks for the advice, i shall have a look at see...
by mikronauts
Wed Apr 12, 2017 9:08 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

10lb should be fine, for some reason I thought I read garage door. Basically the worst thing that can happen from trying the L298N board is that you may smoke the L298N board, just please be careful with the wiring so you don't shock yourself. The link shows a nice large heatsink on the L298N, so it...
by mikronauts
Wed Apr 12, 2017 8:12 pm
Forum: Troubleshooting
Topic: Hardening SD card against power failure?
Replies: 3
Views: 973

Re: Hardening SD card against power failure?

- get one of the many UPS hats - have a background daemon "shutdown now -h" when it detects power loss Hi, not sure if this is the right area in the forum to post so please let me know if you think there is a better place I should be asking. I've been playing with raspberry pi for the past couple of...
by mikronauts
Wed Apr 12, 2017 6:41 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

That motor only has a 6" stroke, what mechanism does it use to move a door that is ~7 feet high? This is the motor I already have in place. I believe it is 0.5 Amp and it looks like the L293D can handle 0.6 Amp. http://www.surpluscenter.com/Brands/VistaMounts/6-Stroke-665-lbs-24-Volt-DC-Linear-Actua...
by mikronauts
Wed Apr 12, 2017 6:37 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

The posted specs say: Amps 0.5 no load We need to know the stall current, which will be significantly higher than the no load current. The L293D would go up in smoke if you tried to move the door with it. In their Q/A, someone asked: What is the amp draw at full load? A: Sorry but we do not have tha...
by mikronauts
Wed Apr 12, 2017 6:01 pm
Forum: Troubleshooting
Topic: Accidentally overpowered the pi
Replies: 17
Views: 1923

Re: Accidentally overpowered the pi

Simple solution:

Buy another RPi3, and give the old one a decent burial.
by mikronauts
Wed Apr 12, 2017 6:00 pm
Forum: Automation, sensing and robotics
Topic: PiZero to control 24VDC bi-directional motor
Replies: 20
Views: 2481

Re: PiZero to control 24VDC bi-directional motor

You need to know the operating voltage and stall current of the motor. Once you know those numbers, you can buy an appropriate motor driver. I have a system in place using some National Instruments hardware to open and close a door at a prescribed time. I am using a relay module in a H-Bridge config...
by mikronauts
Mon Apr 10, 2017 1:31 am
Forum: General discussion
Topic: A/D ops with Raspberry Pi
Replies: 8
Views: 1203

Re: A/D ops with Raspberry Pi

even 100k samples is too much for a Pi

I think joan had 50k samples going once.

The biggest limitation is having to use spi or i2c adc's as there is no easy supported parallel interface on the Pi.
by mikronauts
Mon Apr 10, 2017 1:22 am
Forum: Off topic discussion
Topic: Case study in community: Via APC board
Replies: 3
Views: 1800

Re: Case study in community: Via APC board

I picked up a couple of those and two of the followup "paper" boards from VIA. Appropriate name for a paperweight. I think there is still a google group for it, I got an image there about a year ago as I recall. Just after the Raspberry Pi was launched, a whole bunch of other small ARM boards appear...
by mikronauts
Fri Apr 07, 2017 5:06 pm
Forum: Python
Topic: Hall motor Sensors MCP23017 and PIGPIO
Replies: 9
Views: 1411

Re: Hall motor Sensors MCP23017 and PIGPIO

I really doubt you can do that over I2C, especially if you get multiple pulses per revolution. As I recall, Pi's I2C defaults to 100khz. Each I2C packet for reading a register takes ~30 i2c bit periods at a minimum. For this speed, use the Pi's native pins, in C/C++ with interrupts, or an external m...
by mikronauts
Fri Apr 07, 2017 5:04 pm
Forum: Off topic discussion
Topic: raspberry pi with old tablet
Replies: 5
Views: 3103

Re: raspberry pi with old tablet

Not feasible, would cost more than a new tablet (hdmi adapter board etc) and it would take a TON of software development work (keyboard, touch etc). hello , i dont have enough knowledge about is it possible or not, but i want to upgrade my old asus transformer tf101 with raspberry. this device has a...
by mikronauts
Fri Apr 07, 2017 5:03 pm
Forum: Automation, sensing and robotics
Topic: explorerhat and breakout pins
Replies: 2
Views: 358

Re: explorerhat and breakout pins

Yes, you can hook up more than one module/ic GND pin to a single Pi GND pin. You cannot really share the actual I/O pins, but GND, 5V, and 3V3 may be shared (subject to maximum available current) I need to connect three sensors to breakout pins on the explorerhat, but there are only 2 GND pins avail...

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