Logic... generator? - Page 1
Forum section: electronics / testgear

author: CM800
author_rank: Frequent Contributor
timestamp: February 14, 2014, 11:03:52 am
content: Hello!Im looking for a logic generator.. if such a thing even exists..Basicly i want the inverse of a logic analyzer, somthing i can use to generate all sorts of signals and protocols from I2C to UART to Serial, all sorts.I mostly intend to use it for general testing and experementing.Thanks,Thomas Williamson

author: jpb
author_rank: Super Contributor
timestamp: February 14, 2014, 11:14:39 am
content: A lot of this stuff is built-in to pcs or things like the Rasberry Pi, i.e. anything that (still) has a serial port or a usb port. Otherwise there are pulse generators or the pulse output of general AWGs though these probably only cover two ports which may not be enough. Proto-pic and others do break out boards for I2C and SPI e.g. :http://proto-pic.co.uk/breakout-board-for-sc16is750-i2c-spi-to-uart-ic/?gclid=CI-i_9q9y7wCFUj4wgodMngAowyou could combine that with the serial output of an old laptop or stick a serial card in a desktop computer or use something like a Rasberry Pi. A bit messy but you're doing it for experimentation anyway so it is all part of the learning process. (One caveat, I've not done this myself so I can't definitively say it will work but it is the low-cost route that I would explore if I was wanting to test serial stuff.)

author: jeremy
author_rank: Super Contributor
timestamp: February 14, 2014, 11:29:35 am
content: Yep, they exist:http://en.wikipedia.org/wiki/Digital_pattern_generatorUnfortunately I have not used one before so I can't be of any more assistance.edit: I just realised, I basically have one and use it all the time:http://dangerousprototypes.com/docs/Bus_Pirate, it just can't do true pattern generation

author: kripton2035
author_rank: Super Contributor
timestamp: February 14, 2014, 11:39:21 am
content: I would use an arduino to do that.

author: mrflibble
author_rank: Super Contributor
timestamp: February 14, 2014, 11:40:37 am
content: Two suggestions to pick from based on your preferences:1 - get an mcu dev board, and use DMA to stream your desired pattern to the GPIO pins.2 - get an fpga dev board, and use that to generate patternsThe microcontroller is easier, and an fpga dev board is more versatile for this purpose.mcu dev board: stm32f4 discovery board on the cheap ($15) from digikey/mouser. Or an even cheaper board from the value line.fpga dev board: lattice ice stick on the cheap ($25) from same, or something a bit bigger if you expect to do a lot more fpga mucking aboutWith the mcu you can do about 100 MHz, and with the fpga you can go high enough (400+ MHz) that you run into other problems first.

author: sleemanj
author_rank: Super Contributor
timestamp: February 14, 2014, 12:46:49 pm
content: A Bus Pirate might be along the lines of what you want.http://dangerousprototypes.com/bus-pirate-manual/

author: Phroon
author_rank: Contributor
timestamp: February 14, 2014, 12:59:20 pm
content: Quote from: sleemanj on February 14, 2014, 12:46:49 pmYou beat me by a minute, I had the exact same suggestion.Really useful for bootstrapping peripheral devices, testing out what to send to devices before writing any code, and debugging behavior when they don't do what you expect.

author: nctnico
author_rank: Super Contributor
timestamp: February 14, 2014, 03:05:06 pm
content: It's called a digital pattern generator. Some AWGs have digital outputs and some logic analysers have pattern generator modules. The biggest problem is getting a good software package to create the patterns. Creating an I2C waveform for example is very tedious.

author: grumpydoc
author_rank: Super Contributor
timestamp: February 14, 2014, 04:20:18 pm
content: Keep an eye out for old Tektronix pattern generators on ebay - they pop up from time to time.

author: nctnico
author_rank: Super Contributor
timestamp: February 14, 2014, 04:23:48 pm
content: Quote from: grumpydoc on February 14, 2014, 04:20:18 pmWhich model? The HFS9000 series?

author: rdl
author_rank: Super Contributor
timestamp: February 14, 2014, 04:31:14 pm
content: The Analog Doscovery from Digilent has a pattern generator. $99 student price.http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERYedit: add link

author: Carrington
author_rank: Super Contributor
timestamp: February 14, 2014, 08:09:11 pm
content: This LA also can work as logic funtion generator:http://tools.asix.net/dbg_omega.htmProgram it (the logic funtion) is very boring. But I think that it can "re-transmit" captured data.

author: grumpydoc
author_rank: Super Contributor
timestamp: February 14, 2014, 08:15:21 pm
content: QuoteDG2020's or 2030's occasionally - not always that cheap though.

author: free_electron
author_rank: Super Contributor
timestamp: February 14, 2014, 08:38:12 pm
content: HFS9000 . aaaargh. still have nightmares . That and the DAS series from Trektopnix...the Dg20202 is better (sony Design)

author: jancumps
author_rank: Unknown
timestamp: February 14, 2014, 09:14:33 pm
content: Quote from: free_electron on February 14, 2014, 08:38:12 pmI see what you're doing there...

author: CM800
author_rank: Frequent Contributor
timestamp: February 14, 2014, 10:19:48 pm
content: Thankyou for all the replys, i have an unopened stm32F4 board, i shall use that, if it does not meet what i need, i feel a bus pirate would do best for me, feel free to suggest anything else however too!

author: woodchips
author_rank: Frequent Contributor
timestamp: February 14, 2014, 11:23:48 pm
content: The old HP 8016 or 8018 might do, one is serial and the other parallel output.

author: Hypernova
author_rank: Unknown
timestamp: February 14, 2014, 11:53:15 pm
content: Instead of the bus pirate or straight to the mcu level I would recommend the mbed. Much easier to program and it also got a DAC and CAN.

author: casinada
author_rank: Frequent Contributor
timestamp: February 14, 2014, 11:59:15 pm
content: https://www.usbee.com/

author: Electro Fan
author_rank: Super Contributor
timestamp: February 15, 2014, 12:57:45 am
content: Perhaps a Rigol DP832 or other programmable power supply can be programmed to do rudimentary logic generation? (Seems like a power supply could be programmed to turn voltage up and down to defined levels at defined intervals thereby generating "bits" and creating/generating/representing ASCII character bytes.)

author: nctnico
author_rank: Super Contributor
timestamp: February 15, 2014, 02:07:06 am
content: Quote from: grumpydoc on February 14, 2014, 08:15:21 pmHmm never heard of those. They do look old though. I estimate late 80's / early 90's. I used to have a DAS9200 with pattern generator boards and a Lecroy LW420 with digital outputs. Lack of software made the digital waveform generator very limited.