Search found 12 matches

by roger
Thu Jan 22, 2009 7:41 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

That's about what I can get. Using a 16 bit message size might help, but I have yet to try it.
by roger
Thu Jan 22, 2009 6:49 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

That's a bit of a suspicious result I think.
According to http://forums.obdev.at/viewtopic.php?t=19&postdays=0&postorder=asc&start=0, the theoretical limit is 24kbps and no one got above 7kbps.

Can you post more details and double check your results?
by roger
Wed Jan 21, 2009 10:13 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

Hi. The sample rate is variable and is set by the host (from 1.1 kHz - >10 kHz), and from my testing it is quite accurate. I built a small circuit using an ATTINY85 with a diode and BJT to reduce the 5V USB supply down to ~3.6 V. I used the 16.5 MHz RC module, which is good enough for me. My softwar...
by roger
Mon Jan 19, 2009 7:43 am
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

Sorry I haven't had a chance to post this until now or to clean up my code, but here it is: http://www.megaupload.com/?d=EXUBE3WX

usbtest.c is the main program.

I can almost guarantee there are lots of bugs, so good luck :)
by roger
Thu Jan 15, 2009 5:13 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

Sure, happy to share. Here is the most relevant code: volatile uint8_t adcbuff[250]; // must be multiple of 5 for 10 bit mode volatile uint8_t end = 0; volatile uint8_t start = 0, bytes_ready; volatile uint8_t adc_10bit_mode = 0; #define ADCBufferSize() ((end - start + DAC_BUFF_SIZE&...
by roger
Sun Jan 04, 2009 7:10 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

Thanks, I got it working using a circular buffer and using usbFunctionRead() to send the data.
by roger
Fri Jan 02, 2009 10:00 pm
Forum: V-USB
Topic: Using PCINT1 instead of INT0 on ATTINY45
Replies: 1
Views: 2703

Using PCINT1 instead of INT0 on ATTINY45

Is it possible to do this? I'm not familiar with the driver code so I'm not sure what else will need changing in the header file: /* ----------------------- Optional MCU Description ------------------------ */ /* The following configurations have working defaults in usbdrv.h. You * usually don't nee...
by roger
Mon Dec 29, 2008 9:50 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

I've made some progress and have something that works, but I still need to work out the best way to send the ADC output back to the host. So far I've only tried the default control endpoint, and I can get about 300 bytes/s sending back the ADC contents when requested by the host. FYI the code is som...
by roger
Mon Dec 29, 2008 8:40 pm
Forum: V-USB
Topic: How fast is Software-USB
Replies: 26
Views: 32648

I'm able to get at least 7230 bytes/s (tested with pyUSB) using usbFunctionRead() and sending 254 bytes at a time.
by roger
Wed Dec 24, 2008 9:02 pm
Forum: V-USB
Topic: Continously sampling via ADC, how to start
Replies: 15
Views: 14498

Continously sampling via ADC, how to start

Hi, I'm new to USB programming and would like some advice on how I should proceed. I'm trying to write a program that will continuously (and preferably uniformly) sample a voltage via the integrated ADC on an AVR, and send the values over USB. I'll either use an ADC resolution of 8 or 10 bits and I'...
by roger
Wed Dec 24, 2008 8:50 pm
Forum: V-USB
Topic: Zener diode suitability
Replies: 5
Views: 5105

Thanks Christian, I got EasyLogger working with a ATTINY45 and some diodes I salvaged.
by roger
Sat Dec 20, 2008 5:31 pm
Forum: V-USB
Topic: Zener diode suitability
Replies: 5
Views: 5105

Zener diode suitability

I have a couple 1N4729A 3.6V, 1W zener diodes. Will these work with a 20 MHz clock? I didn't even think about the low power requirement when I bought them.

Thanks,
Roger