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by joan
Tue Aug 14, 2018 11:16 am
Forum: Troubleshooting
Topic: [SOLVED] RPi 3 ttyS0 holds TXD high
Replies: 11
Views: 157

Re: RPi 3 ttyS0 holds TXD high

Set the GPIO back to mode ALT0 to switch it back to UART mode.

I know pigs will do this. http://abyz.me.uk/rpi/pigpio/pigs.html#M/MODES

I'm fairly sure wiringPi's gpio utility lets you select the GPIO modes as well.
by joan
Tue Aug 14, 2018 8:23 am
Forum: Troubleshooting
Topic: Data capture via GPIO
Replies: 7
Views: 148

Re: Data capture via GPIO

If you want help we need the model number.
by joan
Tue Aug 14, 2018 7:55 am
Forum: Troubleshooting
Topic: Data capture via GPIO
Replies: 7
Views: 148

Re: Data capture via GPIO

You could cast a magic spell.

Alternatively if you tell us the type of ADC we might be able to offer advice.
by joan
Tue Aug 14, 2018 7:47 am
Forum: Troubleshooting
Topic: GPIO Pins are always on for some reason
Replies: 5
Views: 110

Re: GPIO Pins are always on for some reason

The 5V power rail pins, the 3V3 power rail pins, and the ground pins are not GPIO.
by joan
Mon Aug 13, 2018 2:58 pm
Forum: Troubleshooting
Topic: [SOLVED] RPi 3 ttyS0 holds TXD high
Replies: 11
Views: 157

Re: RPi 3 ttyS0 holds TXD high

You are mistaken. The line will be held high while there is no traffic. I think that would be the standard for all implementations.
by joan
Sat Aug 11, 2018 9:11 pm
Forum: Advanced users
Topic: dtoverlay=dht11?
Replies: 4
Views: 108

Re: dtoverlay=dht11?

The DHTxx series use a simple checksum rather than a CRC.

For a reliable reader try http://abyz.me.uk/rpi/pigpio/examples.html#pdif2_DHTXXD
by joan
Wed Aug 08, 2018 8:50 pm
Forum: C/C++
Topic: RasberryPi Zero W LED does not turn ON and does not set the GPIO high
Replies: 25
Views: 342

Re: RasberryPi Zero W LED does not turn ON and does not set the GPIO high

rohini wrote:
Wed Aug 08, 2018 8:45 pm
joan wrote:
Wed Aug 08, 2018 8:28 pm
Have you actually tested the LED to see if it works?
Yes I did . I connected it directly to 3.3 Volts and Pin 6 to ground . And it works.
Was that with the LED on the breadboard as in the photo?
by joan
Wed Aug 08, 2018 8:28 pm
Forum: C/C++
Topic: RasberryPi Zero W LED does not turn ON and does not set the GPIO high
Replies: 25
Views: 342

Re: RasberryPi Zero W LED does not turn ON and does not set the GPIO high

Have you actually tested the LED to see if it works?
by joan
Mon Aug 06, 2018 9:12 am
Forum: Troubleshooting
Topic: GPIO pins set to OUT give no voltage high
Replies: 7
Views: 180

Re: GPIO pins set to OUT give no voltage high

Have you run either of the GPIO tests?

Perhaps you could provide a photo of your Pi marked with pin 1 and pin 40.
by joan
Fri Aug 03, 2018 8:48 pm
Forum: Python
Topic: Raspi Zero I2C Speed
Replies: 4
Views: 118

Re: Raspi Zero I2C Speed

Could you explain what you mean by speed?

The default I2C bus rate is 100kbps which equates to 11k bytes per second.

Are you talking about the number of samples per second you get from the ADC? That will be much lower than the bit rate and probably only a third or so of the bytes per second.
by joan
Fri Aug 03, 2018 1:26 pm
Forum: Troubleshooting
Topic: GPIO pins set to OUT give no voltage high
Replies: 7
Views: 180

Re: GPIO pins set to OUT give no voltage high

Perhaps the GPIO are damaged.

wiringPi has a pintest utility.

pigpio has the gpiotest utility.

Both require that nothing is connected to the expansion header during the test.
by joan
Thu Aug 02, 2018 9:51 am
Forum: Python
Topic: GPIO and kivy
Replies: 3
Views: 1539

Re: GPIO and kivy

I suggest you post a general question outlining your task.

A lot of my code examples are done to please me (I enjoy writing software).

If you describe what you want to do in detail I am sure you will get useful replies.
by joan
Thu Aug 02, 2018 2:24 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Sending a string over serial from a raspberry pi using python
Replies: 1
Views: 64

Re: Sending a string over SPI from a raspberry pi using python

SPI is not often referred to as a serial link and is not anything to do with /dev/ttyAMA0.

You probably mean to use /dev/serial0 which is connected to the UART on GPIO 14/15 (pins 8/10).

See https://pinout.xyz/
by joan
Tue Jul 31, 2018 8:46 pm
Forum: Assistive technology and accessibility
Topic: Can a Pi be used in some way to prevent Dementia sufferers making landline calls to a specific number?
Replies: 15
Views: 435

Re: Can a Pi be used in some way to prevent Dementia sufferers making landline calls to a specific number?

Please e-mail her/your MP outlining the problem. They will not be able to directly help but they should be made aware of the problem.
by joan
Tue Jul 31, 2018 11:19 am
Forum: Advanced users
Topic: Using GPIO.add_event_detect in a threading class
Replies: 3
Views: 98

Re: Using GPIO.add_event_detect in a threading class

1. Does the script work and achieve what you want?

2. stop worrying.

use top or similar to see the resources used.
by joan
Mon Jul 30, 2018 6:45 am
Forum: General discussion
Topic: Why must the raspberrypi be so proprietary?
Replies: 41
Views: 1401

Re: Why must the raspberrypi be so proprietary?

The IP creator makes the rules. They decide what intellectual property to defend. The foundation don't own the IP.
by joan
Sun Jul 29, 2018 8:56 am
Forum: Troubleshooting
Topic: How to use BME280 connected with SPI?
Replies: 14
Views: 238

Re: How to use BME280 connected with SPI?

There are 6 wires.

I don't have either of the devices.

Could you explain the connections.

Eg. wire 1 (top) connects BME ? to HAT ?
by joan
Sun Jul 29, 2018 7:02 am
Forum: Python
Topic: Calling variables from different functions
Replies: 6
Views: 232

Re: Calling variables from different functions

Could you explain what you expect to happen and what actually happens? If there is an error the trace back often pinpoints the error.
by joan
Sun Jul 29, 2018 6:59 am
Forum: Troubleshooting
Topic: How to use BME280 connected with SPI?
Replies: 14
Views: 238

Re: How to use BME280 connected with SPI?

I would look at the source code and find out what error causes the error message to appear.

That should give a big clue.

I don't have that software so I will guess that you have not wired up the device correctly.

Could you add some clear photos of the wiring?
by joan
Sat Jul 28, 2018 12:41 pm
Forum: C/C++
Topic: What's wrong with wprintf?
Replies: 2
Views: 134

Re: What's wrong with wprintf?

The stream is either in byte mode or wide char mode. It will only print characters in the corresponding mode.

man fwide

Use fwide(stdout, 1) to set wide char mode.
by joan
Fri Jul 27, 2018 9:09 am
Forum: Troubleshooting
Topic: Interrupted communication via serial (split package)
Replies: 11
Views: 181

Re: Interrupted communication via serial (split package)

The receiver should be designed to cope with slight transmission delays.

I suspect that in this instance the transmitter program is doing a byte by byte transfer. If that is the case then that is an additional problem.
by joan
Fri Jul 27, 2018 7:17 am
Forum: Automation, sensing and robotics
Topic: Controlling five 3v vibration motors from gpio
Replies: 13
Views: 393

Re: Controlling five 3v vibration motors from gpio

One simple way to control your 5 motors with an external 3v supply is to use a ULN2803A 8ch Darlington Sink Driver. ... That makes more sense than using the L9110S that I suggested. You would only need L9110S if you want to drive the motors forwards and backwards which isn't needed for vibration mo...
by joan
Thu Jul 26, 2018 5:30 pm
Forum: Automation, sensing and robotics
Topic: Controlling five 3v vibration motors from gpio
Replies: 13
Views: 393

Re: Controlling five 3v vibration motors from gpio

You shouldn't power any inductive load directly from the Pi GPIO. You will likely destroy the GPIO and the Pi. You can't power these from the GPIO anyhow as they need 70mA each and a GPIO can only safely supply about 20mA. I'd buy three L9110S motor controller boards. The L9110S may be controlled by...
by joan
Thu Jul 26, 2018 5:15 pm
Forum: Raspbian
Topic: rotary-encoder.dtbo
Replies: 2
Views: 87

Re: rotary-encoder.dtbo

The Traveler wrote:
Thu Jul 26, 2018 4:18 pm
https://github.com/raspberrypi/firmware ... t/overlays

Read the README. It's all there.
That does a reasonable job of explaining the set-up. However it provides no information on how to actually read the inputs after it has been set-up.

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