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by chipace
Tue Nov 16, 2021 5:08 am
Forum: General discussion
Topic: Top reasons to move to Bullseye?
Replies: 41
Views: 1925

Re: Top reasons to move to Bullseye?

Thanks for all your insight! I have lots of development libraries installed so I am going to wait. If I get bored around the winter holiday I will give the 64bit Bullseye beta a try then... you can all thank me later when the official 64bit version releases soon after (I am blessed with bad timing).
by chipace
Sun Nov 14, 2021 11:09 pm
Forum: General discussion
Topic: Top reasons to move to Bullseye?
Replies: 41
Views: 1925

Top reasons to move to Bullseye?

I'm thinking about putting off the switch to Bullseye. I read about new features like automatic updates, but none of the listed features are worth the couple of hours of effort for me to move to the new OS version. Are there some really good reasons to upgrade right away? Are there some new librarie...
by chipace
Tue Sep 28, 2021 1:45 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: How can I get a 250,000 bytes transfer over SPI on raspberry pi 4?
Replies: 2
Views: 589

Re: How can I get a 250,000 bytes transfer over SPI on raspberry pi 4?

(1) Change the default spidev.bufsiz=65536 to /boot/cmdline.txt, this gives a 4k byte page size. 250k/4 = 63 pages. (2) Set the SPI frequency to 8MHz (I can run my RPi4b as fast as 16MHz without any errors). This should be a 1MB/s rate with some overhead between each of the 63 transfers. (3) Have th...
by chipace
Sat Jul 24, 2021 8:41 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C scan not detecting a device that the Arduino detects
Replies: 3
Views: 475

Re: I2C scan not detecting a device that the Arduino detects

I would check the GND connection, as a bad connection would explain what you are seeing. You could use a bidir levelshifter and have the 5V level for the device side and the 3.3V for the RPi side... just to see if it truly is an IO level issue. It could be a baud-rate issue as the RPi has a fixed i2...
by chipace
Mon Jul 19, 2021 12:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RPi4 i2c baudrate change without a reboot
Replies: 0
Views: 262

RPi4 i2c baudrate change without a reboot

I am using smbus2 on python to control a couple of i2c slaves using a single bus. It is very convenient for me to use the same bus pins with all the slaves. Is there a command line utility to change the i2c baudrate or something native in python? I tried the nodejs RPIO library but it appears to req...
by chipace
Mon Jul 19, 2021 12:10 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Pi 4 i2c Dead?
Replies: 3
Views: 597

Re: Pi 4 i2c Dead?

I have had the default i2c pins go bad on one of my RPi4 boards. My solution was to swap it with another board that I was using as a media player. You might want to try using a dtoverlay to use different pins. That's the beauty of the RPi4 is many i2c buses.
by chipace
Mon Jul 19, 2021 12:02 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: how to match sending and receiving data in SPI Protocol if not match in output
Replies: 1
Views: 345

Re: how to match sending and receiving data in SPI Protocol if not match in output

Code: Select all

import spidev
spi = spidev.SpiDev(0,0)
spi.max_speed_hz = 12000000
spi.mode = 0b00

byte0 = 0xF0
byte1 = 0xAB
byte2 = 0x34
send_list = [byte0, byte1, byte2]
read_list = spi.xfer2(send_list)
print(read_list)
by chipace
Mon Jun 07, 2021 11:57 pm
Forum: General
Topic: How to confirm uf2 file is for Pico?
Replies: 11
Views: 866

Re: How to confirm uf2 file is for Pico?

One thing to note is that a single UF2 file can validly contain images for a number of different family code devices. That's not so relevant when checking if a UF2 is what one would expect to be generated but is when it comes to reporting what a UF2 file contains. There is also no "UF2 File He...
by chipace
Fri Jun 04, 2021 3:19 am
Forum: General
Topic: How to confirm uf2 file is for Pico?
Replies: 11
Views: 866

Re: How to confirm uf2 file is for Pico?

Thank you all for the good feedback! I decided to fork the github "uf2" repository and add the functionality to util/uf2conv.py . It was literally 15 lines, most of them just print statements. I'll submit a pull request and let them decide if they want the feature. Here is what it looks li...
by chipace
Wed Jun 02, 2021 4:33 am
Forum: General
Topic: How to confirm uf2 file is for Pico?
Replies: 11
Views: 866

Re: How to confirm uf2 file is for Pico?

The four bytes at 28 (decimal = 1C hex) are always FF 56 E4 8B on three Pico UF2's I've looked at. Microsoft define those bytes as "File size or board family ID or zero" which isn't amazingly helpful. hexdump *.uf2 0000000 4655 0a32 5157 9e5d 2000 0000 0000 1000 0000010 0100 0000 0000 000...
by chipace
Wed Jun 02, 2021 3:37 am
Forum: General
Topic: How to confirm uf2 file is for Pico?
Replies: 11
Views: 866

How to confirm uf2 file is for Pico?

Hi, I have been given a uf2 file which was created for the Pico and I wanted to confirm that the file is indeed for the Pico. I have been told that using a hex editor and looking for the family_id would do this, but is there an easier way? Is there a python script similar to uf2conv.py which can par...
by chipace
Sun May 23, 2021 5:43 am
Forum: Advanced users
Topic: Grove Base Kit I2C Usage
Replies: 2
Views: 181

Re: Grove Base Kit I2C Usage

I would first check to see what devices are detected:

Code: Select all

i2cdetect -y 1
If you don't see any detected devices, check that you have good GND, SDA and SCL connections (and 3.3V if your device needs that power from the RPi). You could have the SDA and SCL reversed.
by chipace
Sun May 23, 2021 3:11 am
Forum: General discussion
Topic: MAX6675
Replies: 3
Views: 334

Re: MAX6675

MAX6675 is 12-Bit, 0.25°C Resolution. Zero value is 0C, a value of 1 would be 0.25C. Maximum reading is 4095 decimal which is 1023.75C. Just divide the decimal value you read by 4 and that is the temp in degrees C. No Fahrenheit. Use the datasheet equation to account for ambient temperature in order...
by chipace
Sat May 15, 2021 6:48 pm
Forum: General
Topic: Picoprobe + Logic Analyzer (SUMP protocol)
Replies: 6
Views: 1362

Re: Picoprobe + Logic Analyzer (SUMP protocol)

I really like your project and started looking into SUMP. I also already have a $10 8 pins @24MHz logic analyzer... which is able to saturate the USB 2.0 bandwidth in streaming mode. I believe the next generation of low-cost logic analyzers will be USB 3.0 based and use a FPGA. It will do 16 pins @ ...
by chipace
Wed May 12, 2021 12:52 am
Forum: General discussion
Topic: Raspberry and FPGA
Replies: 27
Views: 10033

Re: Raspberry and FPGA

I am able to program my Xilinx Artix-7 board (cmod a7) from the raspberry pi using xc3sprog. I can either just program the FPGA (which will lose the configuration with a power cycle) or program the SPI Flash (which will be loaded next time the FPGA board is power cycled). https://forum.digilentinc....
by chipace
Sat May 01, 2021 11:47 pm
Forum: General discussion
Topic: Raspberry and FPGA
Replies: 27
Views: 10033

Re: Raspberry and FPGA

I am able to program my Xilinx Artix-7 board (cmod a7) from the raspberry pi using xc3sprog. I can either just program the FPGA (which will lose the configuration with a power cycle) or program the SPI Flash (which will be loaded next time the FPGA board is power cycled). https://forum.digilentinc.c...
by chipace
Sat May 01, 2021 10:10 pm
Forum: General discussion
Topic: RPi4b 2GB out of stock in most of USA
Replies: 5
Views: 2420

Re: RPi4b 2GB out of stock in most of USA

jdb wrote:
Sat May 01, 2021 9:34 pm
https://en.wikipedia.org/wiki/Bullwhip_effect
I think the Trading Company needs to train using the Beer Game.
https://en.wikipedia.org/wiki/Beer_distribution_game
by chipace
Sat May 01, 2021 4:48 pm
Forum: General discussion
Topic: RPi4b 2GB out of stock in most of USA
Replies: 5
Views: 2420

RPi4b 2GB out of stock in most of USA

I am seeing Adafruit, Sparkfun, Pishop, Digikey and Newark all out of stock on RPi4b 2GB boards. A couple of months ago I thought it was due to the ramping of another product, but that does not look like the case. Lots of RPi 400 in stock (no surprise there). Pishop.us still has some 4GB boards, but...
by chipace
Wed Apr 28, 2021 9:57 pm
Forum: General discussion
Topic: spiDev coding help
Replies: 3
Views: 340

Re: spiDev coding help

by chipace
Wed Apr 28, 2021 9:49 pm
Forum: General discussion
Topic: spiDev coding help
Replies: 3
Views: 340

Re: spiDev coding help

If you don't have an oscilloscope or logic analyzer, I would recommend a $10 8channel 24MHz logic analyzer from Amazon.com. The sigrok pulseview program is used to look at the waveforms. It can trigger on edges just like an oscilloscope. It can help debug SPI issues at the hardware level. https://ww...
by chipace
Wed Apr 28, 2021 9:24 pm
Forum: General discussion
Topic: spiDev coding help
Replies: 3
Views: 340

Re: spiDev coding help

This should allow you to read 5 bytes from the device with the first data sent being 0x00 and four "dummy" bytes also with a value of 0x00. Of the 5 bytes in the list_of_bytes, just select the ones you are interested in (most likely you will need to toss the first byte). import spidev spi_...
by chipace
Tue Apr 20, 2021 11:17 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: i2c stopped Working
Replies: 2
Views: 435

Re: i2c stopped Working

I have had one RPi4b board lose i2c functionality. Same issue, does not detect any devices. Oscilloscope showed that the SDA was not driving low when driven by the RPi master (pretty obvious why no slaves gave a NACK). Slave ICs were fine. I just moved that RPi to become a media player instead.
by chipace
Wed Apr 14, 2021 12:01 am
Forum: General discussion
Topic: How can I transmit the data at 1MHz (128 or 256 bit digital data)?
Replies: 5
Views: 388

Re: How can I transmit the data at 1MHz (128 or 256 bit digital data)?

I have used SPI to transmit serial data at 12MHz on the RPi. I would think that it would be just fine. GPIO bit-banging would probably be at a lower data-rate. If you have an oscilloscope that can decode SPI then that could be helpful, otherwise there are 24MHz logic analyzers on Amazon.com that sel...
by chipace
Wed Mar 31, 2021 11:22 pm
Forum: General discussion
Topic: Pi Zero W availability
Replies: 9
Views: 818

Re: Pi Zero W availability

I paid more in shipping for 2 Picos than the sales price when I bought from Pishop.us I saved $2 by ordering from Pishop.us rather than Amazon. I could have had the boards 3 days earlier if I had bought them from Amazon. I hate to say this but the RPi Trading Company would do most people a service b...
by chipace
Wed Mar 31, 2021 11:12 pm
Forum: General discussion
Topic: VNC on Headless Raspberry Pi
Replies: 4
Views: 390

Re: VNC on Headless Raspberry Pi

I find it ironic that I run headless with VNC 95% of the time when doing projects... when the RPi4b has dual HDMI 2.0 ports.

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