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by joan
Sat Dec 14, 2019 8:54 am
Forum: Beginners
Topic: GPIO assignments
Replies: 1
Views: 25

Re: GPIO assignments

No, there is not. You will have to trace the wiring yourself.
by joan
Tue Dec 10, 2019 9:52 am
Forum: C/C++
Topic: Help with GPCLK setup? My register assignments aren't working?
Replies: 7
Views: 171

Re: Help with GPCLK setup? My register assignments aren't working?

See http://abyz.me.uk/rpi/pigpio/cif.html#gpioHardwareClock notes.

You are probably screwing up the system when you write to clock 1 (used by GPIO 5).

Another code example.

https://github.com/joan2937/pigpio/blob ... o.c#L12705
by joan
Sun Dec 08, 2019 8:27 am
Forum: General discussion
Topic: Device not detected using i2c-detect y 1
Replies: 10
Views: 251

Re: Device not detected using i2c-detect y 1

If you have a ribbon cable between the Pi and breadboard it may be inserted the wrong way around at one end.
by joan
Sat Dec 07, 2019 4:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: i2c and IOError: [Errno 121] Remote I/O error
Replies: 2
Views: 90

Re: i2c and IOError: [Errno 121] Remote I/O error

That error is invariably poor or wrong wiring. A photo clearly showing the connections may help.
by joan
Fri Dec 06, 2019 2:14 pm
Forum: Automation, sensing and robotics
Topic: Photoresistor without ADC
Replies: 2
Views: 129

Re: Photoresistor without ADC

Put your light dependent resistor as shown here. 3V3 ----- Resistor --+-- Capacitor ----- Ground | +-- GPIO Perhaps start from low value capacitors and work up until you find a suitable value. Example code at http://abyz.me.uk/rpi/pigpio/examples.html#Python_pot_cap_py
by joan
Thu Dec 05, 2019 8:34 pm
Forum: General discussion
Topic: Command to check GPIO'S?
Replies: 13
Views: 365

Re: Command to check GPIO'S?

GPIO14 has always been serial TXD which is high by default. It sounds like you have enabled the console or serial link. You can use raspi-config to disable this behaviour.
by joan
Thu Dec 05, 2019 3:11 pm
Forum: C/C++
Topic: Use of system timers
Replies: 8
Views: 251

Re: Use of system timers

Perhaps you need to clarify your question.
by joan
Thu Dec 05, 2019 2:59 pm
Forum: C/C++
Topic: Use of system timers
Replies: 8
Views: 251

Re: Use of system timers

man nanosleep
by joan
Thu Dec 05, 2019 10:25 am
Forum: Beginners
Topic: Hall effect sensor
Replies: 20
Views: 548

Re: Hall effect sensor

This just highlights many points familiar to anyone who has ever tried to write documentation. Many won't read it in the first place and of those that do some will find the most perverse interpretation of your words.
by joan
Thu Dec 05, 2019 10:07 am
Forum: General discussion
Topic: GPIO Pins
Replies: 4
Views: 149

Re: GPIO Pins

GPIO 0 and 1 are an unfortunate choice as they are meant to be reserved for HAT use (and possibly the camera as well).

Could you change your software to pick any two from say GPIO 4 to GPIO 27 instead?
by joan
Thu Dec 05, 2019 10:03 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO 4 as an Interrupt Pin on RaspberryPi Model 4B
Replies: 4
Views: 200

Re: GPIO 4 as an Interrupt Pin on RaspberryPi Model 4B

All the GPIO on the expansion header can generate an interrupt on level change. So as long as your input to GPIO 4 causes it to change from detecting 3V3 to detecting ground (or vice versa) it will work.
by joan
Wed Dec 04, 2019 8:01 am
Forum: Beginners
Topic: Hall effect sensor
Replies: 20
Views: 548

Re: Hall effect sensor

You are using GPIO 8 in the software. I can see nothing connected to GPIO 8.

https://pinout.xyz/
by joan
Tue Dec 03, 2019 5:31 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI: Too short delay between CS low and first byte
Replies: 4
Views: 177

Re: SPI: Too short delay between CS low and first byte

The simplest way would be for you to toggle the CS GPIO yourself.

Code: Select all

set GPIO low
do SPI transfer
set GPIO high
If your SPI driver must drive CS itself just don't connect the GPIO it is using for CS and connect your selected GPIO as CS.
by joan
Tue Dec 03, 2019 5:09 pm
Forum: Python
Topic: reading value from mcp3008 takes half a second
Replies: 4
Views: 129

Re: reading value from mcp3008 takes half a second

There is a chance that you are being starved of time because the process consumes 100% of the CPU in the while loop. Change continue to time.sleep(1).
by joan
Tue Dec 03, 2019 3:19 pm
Forum: C/C++
Topic: C++ callback upon gpio state change with pigpio
Replies: 21
Views: 833

Re: C++ callback upon gpio state change with pigpio

I have no way of testing at the moment (no access to a Pi). I guess networking will be the bottleneck. I'd try to generate level changes at the Pi with PWM and monitor them on your laptop with piscope. When piscope starts obviously missing level changes that is probably saturation point as far as th...
by joan
Mon Dec 02, 2019 10:13 pm
Forum: Assistive technology and accessibility
Topic: GPIO and Servo Motor Help (Braille Display)
Replies: 5
Views: 320

Re: GPIO and Servo Motor Help (Braille Display)

An external power supply is recommended. A servo under load can easily draw a couple of amps at 5V which is more than a Pi can supply. However I often use one or more 9g servos directly powered from the Pi.
by joan
Mon Dec 02, 2019 8:15 pm
Forum: Assistive technology and accessibility
Topic: GPIO and Servo Motor Help (Braille Display)
Replies: 5
Views: 320

Re: GPIO and Servo Motor Help (Braille Display)

Servos have three wires. Two are for power and ground, the third for control. A GPIO is only used to supply the control signal and far less than 16 ma is required.
by joan
Sun Dec 01, 2019 4:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C recognized but no output
Replies: 3
Views: 131

Re: I2C recognized but no output

The downloaded file should be called i2c_lcd.py

The daemon may be already installed. Try sudo pigpiod
by joan
Sun Dec 01, 2019 4:29 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RPi4 and i2c; Has anyone used additional i2c buses?
Replies: 14
Views: 2074

Re: RPi4 and i2c; Has anyone used additional i2c buses?

The problem is because you have no pull ups to 3V3 connected to your new I2C buses. You could set the internal pull-ups on those GPIO but they are too weak to be reliable. Try something like 4k7 external pulls to 3V3.
by joan
Sun Dec 01, 2019 3:49 pm
Forum: Beginners
Topic: GPIO Pin still output 3.3V after the ending the script
Replies: 2
Views: 153

Re: GPIO Pin still output 3.3V after the ending the script

Change the GPIO to be an INPUT.

Which GPIO are you using? Only a few are likely to be set as an OUTPUT after reboot.
by joan
Sun Dec 01, 2019 1:22 pm
Forum: C/C++
Topic: UART Problem
Replies: 17
Views: 465

Re: UART Problem

Okay.

Can you post a complete program with build instructions. We can then do exactly what you do.
by joan
Sun Dec 01, 2019 12:15 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C recognized but no output
Replies: 3
Views: 131

Re: I2C recognized but no output

Try http://abyz.me.uk/rpi/pigpio/examples.h ... i2c_lcd_py

It needs the pigpio daemon running (sudo pigpiod).
by joan
Sun Dec 01, 2019 10:34 am
Forum: C/C++
Topic: UART Problem
Replies: 17
Views: 465

Re: UART Problem

Perhaps you are not using Raspbian?

What does ls -l /dev/serial* report?
by joan
Sun Dec 01, 2019 9:01 am
Forum: C/C++
Topic: raspberry pi3 HX711 using loadcell Segmentation fault
Replies: 5
Views: 231

Re: raspberry pi3 HX711 using loadcell Segmentation fault

Unchange the code? Does it still give a segmentation fault.

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