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by joan
Thu Sep 20, 2018 5:44 pm
Forum: Compute Module
Topic: I2C Problems on SDA
Replies: 25
Views: 372

Re: I2C Problems on SDA

I do not understand what you mean by "When I add 220 Ohm series resistors to SCL and SDA at the slave side". I guess one side is connected to SDA/SCL. What is the other end connected to?
by joan
Thu Sep 20, 2018 7:26 am
Forum: Python
Topic: abort pigpiod wave_chain?
Replies: 3
Views: 85

Re: abort pigpiod wave_chain?

wave_tx_stop() will work.
by joan
Wed Sep 19, 2018 7:30 am
Forum: Camera board
Topic: wildlife cam help
Replies: 14
Views: 319

Re: wildlife cam help

How much is in your budget. You could buy a decent motion detect security camera to record to internal SD card for less than a 100 GBP.
by joan
Mon Sep 17, 2018 5:22 pm
Forum: Beginners
Topic: i2c address conversion
Replies: 2
Views: 80

Re: i2c address conversion

I'm not sure what you want. You can write 3d as 0x3D if you want. I think you need to clarify what you want to achieve.
by joan
Sun Sep 16, 2018 10:05 pm
Forum: General discussion
Topic: If I connect 5V output sensor directly with raspberry pi 3b+ so it is harmful for my raspberry pi. Yes or No?
Replies: 4
Views: 171

Re: If I connect 5V output sensor directly with raspberry pi 3b+ so it is harmful for my raspberry pi. Yes or No?

There is no general answer for a sensor. There is not even a simple answer for the DHT11 as many are built into modules with extra circuitry on board. If you mean the 4 pin DHT11 sensor then the following applies. The DHT11 will work when powered from 3V3. If you do that you don't have to worry abou...
by joan
Sat Sep 15, 2018 5:34 pm
Forum: Beginners
Topic: reading and logging pin status of arduino with my rpi
Replies: 12
Views: 154

Re: reading and logging pin status or arduino with my rpi

You could use a resistor divider to drop the 5V Arduino output to a Pi safe 3V3. E.g. https://learn.sparkfun.com/tutorials/voltage-dividers https://en.wikipedia.org/wiki/Voltage_divider There will be plenty of Python code to base yours on. E.g. (my) http://abyz.me.uk/rpi/pigpio/examples.html#Python_...
by joan
Sat Sep 15, 2018 8:02 am
Forum: Graphics programming
Topic: gcc error: main.c No such file or directory
Replies: 4
Views: 128

Re: gcc error: main.c No such file or directory

Could you repeat the command and also do a ls -l before hand? Cut & paste the terminal input and output so we can double check the commands being given.
by joan
Fri Sep 14, 2018 3:48 pm
Forum: Advanced users
Topic: Raspberry Pi GPIO at 3.5V
Replies: 2
Views: 140

Re: Raspberry Pi GPIO at 3.5V

For peace of mind I would buy one which uses 3V3.
by joan
Fri Sep 14, 2018 7:38 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C read always get first byte
Replies: 8
Views: 245

Re: I2C read always get first byte

I would get rid of the serial prints from within the Arduino interrupt handlers. They could be delaying the I2C bus.
by joan
Thu Sep 13, 2018 11:27 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C read always get first byte
Replies: 8
Views: 245

Re: I2C read always get first byte

We need to see the Arduino code.
by joan
Thu Sep 13, 2018 9:14 pm
Forum: Python
Topic: a multiprocessing?
Replies: 4
Views: 153

Re: a multiprocessing?

top or ps should help.
by joan
Thu Sep 13, 2018 8:42 am
Forum: Troubleshooting
Topic: SPI Broken - No Signals
Replies: 11
Views: 254

Re: SPI Broken - No Signals

The tutorials would have been correct when they were written. The situation is pretty stable nowadays buts it's probably always a good idea to check the tutorial date (when given).
by joan
Thu Sep 13, 2018 7:48 am
Forum: Troubleshooting
Topic: Using timer in GPIO numbering error
Replies: 10
Views: 207

Re: Using timer in GPIO numbering error

Could you post a clear photo showing the Pi and wiring? We can then check the GPIO numbering is correct.
by joan
Thu Sep 13, 2018 6:20 am
Forum: Troubleshooting
Topic: Using timer in GPIO numbering error
Replies: 10
Views: 207

Re: Using timer in GPIO numbering error

Are you still getting the same error?
by joan
Wed Sep 12, 2018 4:59 pm
Forum: Troubleshooting
Topic: SPI Broken - No Signals
Replies: 11
Views: 254

Re: SPI Broken - No Signals

Open a terminal window (there should be a GUI menu option). Type the lines without the ( at the start.
by joan
Wed Sep 12, 2018 3:54 pm
Forum: Troubleshooting
Topic: SPI Broken - No Signals
Replies: 11
Views: 254

Re: SPI Broken - No Signals

sudo pigpiod

pigs spio 0 100000 0 # Open channel 0 at 100kbps in mode 0

(the above should return 0 as the "handle")

pigs spix 0 11 12 13 14 15 16

(the 0 is the returned "handle")

Anything on the scope?
by joan
Wed Sep 12, 2018 2:28 pm
Forum: Troubleshooting
Topic: SPI Broken - No Signals
Replies: 11
Views: 254

Re: SPI Broken - No Signals

Use different software? Probably hundreds of thousands of people use SPI on the Pi. They would have noticed if it was broken.

If you want to know what you are doing wrong you need to give information about your set up.
by joan
Wed Sep 12, 2018 10:34 am
Forum: Troubleshooting
Topic: Using timer in GPIO numbering error
Replies: 10
Views: 207

Re: Using timer in GPIO numbering error

Python is case sensitive.

global StepPIns

should be

global StepPins
by joan
Wed Sep 12, 2018 9:32 am
Forum: Troubleshooting
Topic: MCP23017 interrupts
Replies: 41
Views: 569

Re: MCP23017 interrupts

I do not remember seeing any problem. You connect a wire to a GPIO and then touch the wire with a hand which then triggers an interrupt. That is expected behaviour.
by joan
Tue Sep 11, 2018 6:37 pm
Forum: Python
Topic: Quadrature encoder serial pins question
Replies: 11
Views: 143

Re: Quadrature encoder serial pins question

I don't understand how the code you linked is relevant to the encoder. Have you got a circuit diagram to show the intended usage?
by joan
Tue Sep 11, 2018 6:35 pm
Forum: Python
Topic: Quadrature encoder serial pins question
Replies: 11
Views: 143

Re: Quadrature encoder serial pins question

You can use a pair of resistors of the same value as a resistor divider. You need one pair for A and another pair for B. That will drop the output voltage from 5V to a Pi safe 2.5V (still high enough to be seen as logic high at the Pi).
by joan
Tue Sep 11, 2018 5:59 pm
Forum: Python
Topic: Quadrature encoder serial pins question
Replies: 11
Views: 143

Re: Quadrature encoder serial pins question

It has contacts marked A B I - + (not in that order).

Connect A and B to separate GPIO. Connect - to a Pi ground (say pin 6) and + to 5V (say pin 2). You may leave I unconnected. Configure the software you are using by specifying the GPIO connected to A and B.

https://pinout.xyz/
by joan
Tue Sep 11, 2018 8:47 am
Forum: Troubleshooting
Topic: MCP23017 interrupts
Replies: 41
Views: 569

Re: MCP23017 interrupts

fisherijus wrote:
Tue Sep 11, 2018 8:36 am
i tried connecting it to 10k and it did not work....i also found couple of solutions on the internet that use same schemantic and they don't
encounter these kind of problems.
10k is a pretty weak pull. Perhaps try 5k or even 2k (or stop touching the wire).
by joan
Tue Sep 11, 2018 8:28 am
Forum: Troubleshooting
Topic: MCP23017 interrupts
Replies: 41
Views: 569

Re: MCP23017 interrupts

I'm not convinced there is an actual problem. If the interrupt only occurs when you touch the wire that would suggest a stronger pull is needed.

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