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by RedDragon
Sun Apr 28, 2019 12:14 pm
Forum: C/C++
Topic: Time measurement
Replies: 3
Views: 265

Re: Time measurement

Thank you for replies! I tried POSIX time stamp, too, with the same results. I think joan has right, there is a jitter between GPIO change and reading the time stamp. The time stamp must be always correct in all kind of solution, but GPIO change -> reading jitter should be avoided somehow or stabili...
by RedDragon
Sun Apr 28, 2019 10:51 am
Forum: C/C++
Topic: Time measurement
Replies: 3
Views: 265

Time measurement

I am working on an RC meter. It's need four digit time measurement. I have tried nanosleep, interrupt routines, but all that fail with three digit repetability. As an alternative IRQ I would like to use DMA initiated by GPIO. Sounds crazy, but if the RX periferies selected to the GPIO can initiate a...
by RedDragon
Sun Apr 28, 2019 3:54 am
Forum: C/C++
Topic: How to set FIQ to GPIO
Replies: 0
Views: 119

How to set FIQ to GPIO

I am working on an RC meter. The measurement requires four digit precision of time measurement. I have tried using nanosleep,pigpio, direct gpio interrupt routin, but I could reach only three stable digits. Direct interrupt programming called my attention to FIQ which may solve the problem. What pla...
by RedDragon
Thu Apr 18, 2019 11:38 am
Forum: Automation, sensing and robotics
Topic: msec timing
Replies: 6
Views: 245

Re: msec timing

Hardware is set to 10sec periode. The output: pi@raspberrypi:~/MyC/Raspberry/source/RCM/1% $ sudo ./RM2 -C -8 9598089 9.880 MOhm 9591959 9.874 MOhm 9590603 9.872 MOhm 9588335 9.870 MOhm 9588270 9.870 MOhm 9588054 9.870 MOhm 9587138 9.869 MOhm 9587929 9.870 MOhm 9586499 9.868 MOhm 9587389 9.869 MOhm ...
by RedDragon
Thu Apr 18, 2019 4:40 am
Forum: Automation, sensing and robotics
Topic: msec timing
Replies: 6
Views: 245

Re: msec timing

I evaluated the gpioSetAlertFunc function. The program is very nice and short, but unfortunatelly, the tick reading is flucktuating in the fourth digit independently if I was working in 10 sec or 1 sec range. Do you have any idea how to reach stable four digit?
by RedDragon
Wed Apr 17, 2019 3:26 pm
Forum: Automation, sensing and robotics
Topic: msec timing
Replies: 6
Views: 245

Re: msec timing

Thank you Joan for the example and for the idea. I will let you know how does this work in my case. I also come back with the schematic of the meter. The difference is in the hardware, which is linear by nature of an integrator. It simple for a beginner, easy to assemble (actually work on a breadboa...
by RedDragon
Wed Apr 17, 2019 12:23 pm
Forum: Automation, sensing and robotics
Topic: msec timing
Replies: 6
Views: 245

msec timing

I have assembled a simple 4 digit 1% precision RC meter. I will publish it under GPL soon, but there is something back in the software. I need to measure time 4 digit precisely in sec and msec range. nanosleep() does not give the required stability, in the fourth digit there is an "instability". I w...
by RedDragon
Fri Dec 14, 2018 3:00 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2351

Re: SPI + GPI interface

Thank you for the suggestions. I have made a small testboard and some small program (they still need some "finishing"), but it works.

Laszlo
by RedDragon
Wed Nov 21, 2018 5:49 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2351

Re: SPI + GPI interface

Thank you for take a look at the device datasheet. Points still open how can I control the device. According to the datasheet it needs 32 bit word length and Raspberry can transfer 8 bit words. Linux driver can transfer that in multibyte form, as I start to understand but it still needs further inve...
by RedDragon
Tue Nov 20, 2018 8:21 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2351

SPI + GPI interface

Hello,

I am thinking on connecting ADS8685 analog input to a raspberry pi zero. It needs 32 bit spi datatransfer and needs some gpio to full utilization. I am looking for a good solution handle the signals. Any idea which may work welcomed.
Thanks in advance!
by RedDragon
Thu Jun 14, 2018 10:21 am
Forum: Automation, sensing and robotics
Topic: Digital VoltMeter for beginners
Replies: 3
Views: 487

Digital VoltMeter for beginners

I am looking for experienced programmermate to construct a digital voltmeter application. The project is based on MSP430 microcontroller with Raspberry Pi. The microcontroller function as a low frequency 16bit+sign resolution 26V maximum input VoltMeter. It has an OLED 0.91" display for standalone m...
by RedDragon
Sun Jun 03, 2018 3:48 pm
Forum: Automation, sensing and robotics
Topic: piscope
Replies: 7
Views: 1124

Re: piscope

Thank you for the advice! It works fine. I already got the idea what could be wrong with my program.
Thanks again,

RedDragon
by RedDragon
Sun Jun 03, 2018 6:22 am
Forum: Automation, sensing and robotics
Topic: piscope
Replies: 7
Views: 1124

Re: piscope

After a long time of offline brekee12 changed to RedDragon. I forget to write the PiScope is installed on Ubuntu 16 and and it takes a long time to see signals (>5 sec) from RPi and live view does not updates just acquire 3 sec? Something happens because at 3 sec there is a signal change so the prog...

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