JUst thought of a brilliant next project! - Page 1
Forum section: electronics / general

author: commie
author_rank: Frequent Contributor
timestamp: October 08, 2015, 06:49:39 pm
content: Hi,I have looked around the net for a basic digital pattern generator-(parallel based) and there is nothing that's low cost. So, I reckon I could make one using an AVR but unfortunately, I'm tied up at the minute with something else.Anyhow, what do you think?, if you can find one for about $100.00 then post it here and lets see it.CheersCommie

author: bitslice
author_rank: Frequent Contributor
timestamp: October 08, 2015, 06:54:44 pm
content: I was thinking along the lines of a lot of parallel load shift registers and 8-dip switches, simply because 100pcs tend to go for pennies, and it would cut down on software.Something like a Bus Pirate is another approach.https://www.coolcomponents.co.uk/bus-pirate-v4.html

author: commie
author_rank: Frequent Contributor
timestamp: October 08, 2015, 07:19:10 pm
content: Quote from: bitslice on October 08, 2015, 06:54:44 pmBus Pirate can decode all the serial protocols, that's not really what I had in mind.Rather a attiny2313 with two separate 4 - bit outputs that can count up/down, speed up using rotary encoder, buffered buses with led's showing current output. I'm sure I could do this with just a few lines of compiler code.Note, my scope does serial bus decode, so I don't need another one.

author: bitslice
author_rank: Frequent Contributor
timestamp: October 08, 2015, 07:30:12 pm
content: (I think) bus pirate can alsooutputwhatever bitstream you like?For me, I was thinking along the lines of simulating a 8 bit CPU memory/IO/INT cycle,so auto inc address, data + controls

author: Kalvin
author_rank: Super Contributor
timestamp: October 08, 2015, 07:35:08 pm
content: An MCU with a DMA could be helpful. For the best performance an FPGA-based solution could be justified. The MCU would fill the SRAM inside the FPGA with the pattern to be spit out and the state machine inside the FPGA would play the pattern. Even an Arduino + a cheap FPGA should be sufficient.

author: commie
author_rank: Frequent Contributor
timestamp: October 08, 2015, 08:23:41 pm
content: Quote from: Kalvin on October 08, 2015, 07:35:08 pmWhy do we need fpga?, you would have determined the max clock speed before the design commenced. In actual fact a slow single step output count/up/dn pattern would be sufficient to verify your logic function. So one could see the states happening with a slow sequence of events of your circuit.

author: commie
author_rank: Frequent Contributor
timestamp: October 08, 2015, 08:29:17 pm
content: Quote from: bitslice on October 08, 2015, 07:30:12 pmWhy bother with cpu's in this day and age? Unless you are on a learning cycle perhaps?, use an AVR/PIC/8051 instead.

author: bitslice
author_rank: Frequent Contributor
timestamp: October 08, 2015, 08:37:23 pm
content: Quote from: commie on October 08, 2015, 08:29:17 pmI never got around to building that overly complex rack mounted Z80 system when I was a kid, so that is why I'm getting back into electronics nowI do have a pile of PIC/AVR/ST8/CPLD stuff which is waiting attention, but they don't hold the same interest. I mean, on board ram and I/O? Pffft, that's just decadent

author: commie
author_rank: Frequent Contributor
timestamp: October 09, 2015, 09:52:12 am
content: Quote from: bitslice on October 08, 2015, 08:37:23 pmYeah, I know what you mean, I have massive stocks of AVR as well, I am thinking of doing a Z80 project myself which would run basic.