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by tony1tf
Sat May 08, 2021 8:56 am
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

I do regular searches but havn’t seen an update yet. What’s happening at R Pi hq? Presumably there are marketing issues and huge numbers of chips that third parties have built into RP2040 boards. I guess a new fabrication run costs huge amounts of money, so it will have to incorporate some new featu...
by tony1tf
Sun Mar 21, 2021 4:03 pm
Forum: Camera board
Topic: HQ camera as all sky cam
Replies: 60
Views: 8255

Re: HQ camera as all sky cam

RoboRob wrote:switch off the Image Details setting...
Wow - that was quick Rob, and it worked - thank you!
Presumably this is bug that can be fixed if we want to see those details?
Tony
by tony1tf
Sun Mar 21, 2021 2:26 pm
Forum: Camera board
Topic: HQ camera as all sky cam
Replies: 60
Views: 8255

Re: HQ camera as all sky cam

I am having problems in the HQ camera display - live or saved, and full size or 2X2 binned - there is a white line across the image about one quarter down, and a red line above it. I have attached part of a screen dump showing this. Does anyone have a fix, please?
Tony
allsky_line.png
allsky_line.png (255.54 KiB) Viewed 529 times
by tony1tf
Tue Mar 16, 2021 6:52 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

This looks like a good research of the ADC diff non-linearity: https://pico-adc.markomo.me/INL-DNL/ Excellent article - thank you. James Allen has posted that they are working on it, so I am pleased that we have all contributed to the update. It will be interesting to know what the work arounds are...
by tony1tf
Wed Mar 10, 2021 8:41 pm
Forum: Troubleshooting
Topic: RPi 400 Philips TouCam Fixed
Replies: 0
Views: 72

RPi 400 Philips TouCam Fixed

The broken pwc driver has now been fixed in the latest OS update 5.10.20-v7+ available with sudo rpi-update.
I can confirm that the Philips ToUcam now works with the RPi 400.

Tony
by tony1tf
Wed Mar 10, 2021 1:22 pm
Forum: Camera board
Topic: HQ camera as all sky cam
Replies: 60
Views: 8255

Re: HQ camera as all sky cam

create a file in /home/pi/allsky named autocam.sh and put in it: export CAMERA=RPiHQ change the settings of the file to 755: chmod 755 autocam.sh that should fix the issue... Hi Rob Thanks for that post. I will also post it on the Facebook group where I have said that I don't get the camera paramet...
by tony1tf
Wed Mar 10, 2021 10:59 am
Forum: Troubleshooting
Topic: "Creeping" SD Card Space Loss
Replies: 42
Views: 1323

Re: "Creeping" SD Card Space Loss

Thank you all for this very useful thread for Linux newbies. Running this: #!/bin/bash pi@allsky:~ $ find /var/* -type f -mtime -1 -print >> list.txt creates a number of permission denied messages - eg: find: ‘/var/cache/private’: Permission denied find: ‘/var/cache/cups’: Permission denied The next...
by tony1tf
Sat Feb 27, 2021 11:08 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

id check the ripple with a scope, to see if the pwm is being abnormally low ripple at certain levels, but i find it extremely unlikely that 3 different methods all wind up perfectly hanging at 511, definitely looks like the adc is being funky I changed the low pass filter to get even lower noise le...
by tony1tf
Fri Feb 26, 2021 1:10 am
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

that gives me a new idea try holding the pwm at a certain duty cycle, and then grab a histogram for that one duty cycle how stable does the adc claim your pwm->analog->digital path is? do certain duty cycles near the weird peaks, still show that weird peak? does a scope agree with the stability the...
by tony1tf
Thu Feb 25, 2021 12:06 pm
Forum: Troubleshooting
Topic: RPi 400 Philips TouCam
Replies: 6
Views: 307

Re: RPi 400 Philips TouCam

Hi Gordon P33m seems to be understanding the problem on github raspberrypi/linux/, that it is to do with DMA mapping, but he says it is unique, so maybe there is a problem with standard firmware on the RPi. https://github.com/raspberrypi/linux/issues/4174 I don't know whether he can fix it, though. ...
by tony1tf
Wed Feb 24, 2021 11:56 pm
Forum: General
Topic: Setting PWM Frequency - odd results
Replies: 4
Views: 261

Re: Setting PWM Frequency - odd results

Can you dump the contents of the CHx_DIV registers in the PWM block for each of your settings? Quite tricky - it seems that 3 registers are involved - CSR, DIV and TOP. Here are the frequency setting numbers and register values for PWM channel 2 associated with GPIO21: PWM2 Freq = 900000 Hz PWM CH2...
by tony1tf
Wed Feb 24, 2021 6:23 pm
Forum: Troubleshooting
Topic: RPi 400 Philips TouCam
Replies: 6
Views: 307

Re: RPi 400 Philips TouCam

Thanks for your confirmation Gordon. Who do we badger to get it fixed?
I have posted a bug report on git hub raspberrypi/linux.
Tony
by tony1tf
Tue Feb 23, 2021 6:52 pm
Forum: Troubleshooting
Topic: RPi 400 Philips TouCam
Replies: 6
Views: 307

RPi 400 Philips TouCam

Has anyone succeeded in getting the Philips TouCam working on the Raspberry Pi 400 in Buster? I am getting an error if I try and select it in VLC: libv4l2: error turning on stream: cannot allocate memory The camera is detected in lsusb: Bus 001 Device 005: ID 0471:0311 Philips (or NXP) PCVC740K ToUc...
by tony1tf
Sat Feb 20, 2021 8:10 pm
Forum: General
Topic: DIP Socket for Pico?
Replies: 8
Views: 531

Re: DIP Socket for Pico?

I'm sure it's not impossible to bend the pins in by 0.05" each side to fit in a standard 0.6" wide socket.
by tony1tf
Sat Feb 20, 2021 7:54 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

I decided to play around a bit with PWM frequencies to see if it made much difference. I made sure that the settling time was sufficient for the signal to be stable and ran my code again. This is with PWM = 100 kHz. I also tried 1 MHz - none make any significant difference. BTW, I note there is a ma...
by tony1tf
Sat Feb 20, 2021 2:32 pm
Forum: General
Topic: Setting PWM Frequency - odd results
Replies: 4
Views: 261

Setting PWM Frequency - odd results

I have just been monitoring a GPIO PWM output set at around 1MHz with the name.freq(1000000) command in MicroPython. It wasn't quite accurate - 992.086 kHz. So I tried adjusting the number to get to exactly 1MHz and found that it doesn't set a monotonic range of value. Here are some examples: 900000...
by tony1tf
Sat Feb 20, 2021 9:40 am
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 23
Views: 3099

Re: gpu_fft for RPi4?

Last time I did anything (*) with FFTs I found that FFTW running on the ARM was fast enough for my needs and easier to use than the GPU based library. PeterO (*) https://www.youtube.com/watch?v=89fJKpPgAsU Hi Peter, did this project continue? Which rf front end were you using? The video snippet loo...
by tony1tf
Fri Feb 19, 2021 12:35 pm
Forum: SDK
Topic: 1-Wire™ library needs testing
Replies: 22
Views: 1240

Re: 1-Wire™ library needs testing

Hi bgolab Thanks for that link to using a UART for 1-wire comms - a waste maybe, but if it isn't being used for anything else, why not? Something I had never considered. I use bit banging libraries for 1-wire comms on an arbitrary pin on both my home system OpenPi (uses an original compute module), ...
by tony1tf
Mon Feb 15, 2021 4:32 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

I decided to improve the ADC's DNL, by using the Gatti sliding scale method that I previously spoke about. I have speeded up the PWM time constant by using a 10K and 0.1uF cap. I have rewritten the code to add an offset to the ramp from a random number generator where you can set the number of bits....
by tony1tf
Sat Feb 13, 2021 10:00 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

Hi scruss and bgolab

Thanks for that - great to see the same results. Using PWM gives the same results, as does the noisy/quiet power settings. I await comments from the silicon team.

Tony
by tony1tf
Sat Feb 13, 2021 9:21 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

Hi Scruss and others, Your circuit is OK apart from - I used a 100K ohm resistor, and output from GP22 on pin 29. My set up is shown in the attached photograph - wires pushed into the card on which the Pico came with HackSpace Magazine! IMG_1059.JPG As for use of PWM - as I said previously, I did tr...
by tony1tf
Sat Feb 13, 2021 4:58 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

Has anyone else performed this experiment? I would like to see if you get similar results to me. The graph posted by bgolab is not similar, since it is not a histogram, but an input to output function curve, and also has the resolution cut down to 8 bits. When I ran at 8 bit resolution, the DNL at v...
by tony1tf
Wed Feb 10, 2021 7:19 pm
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

I found out how to access the ADC registers and set up a structure with uctypes. If there is a simpler way than this in MicroPython, please let me know. import uctypes ADC_BASE = 0x4004c000 # base address of ADC registers # set up structure of the ADC register block adc_layout = { "CS": 0 ...
by tony1tf
Wed Feb 10, 2021 1:10 am
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

I haven't tried the ADC yet, but I confirm that with micropython it is quite doable to set up and use 'missing' peripherals with direct register access, either through the mem32[] function or the viper pointers. As example I point here to an AWG implementation I posted yesterday on instructables. I...
by tony1tf
Tue Feb 09, 2021 11:15 am
Forum: General
Topic: ADC Differential Non-Linearity
Replies: 63
Views: 3714

Re: ADC Differential Non-Linearity

Here's the latest full histogram with the PWM sweep going from 100 to 4000 at the ADC input after the LPF. Stopped when the 511 glitch got over 1000. It's still showing those big glitches and constant small ones
Hist_all_PWM.png
Hist_all_PWM.png (225.8 KiB) Viewed 1175 times

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