Programmable Delay Circuit - Page 1
Forum section: electronics / general

author: Md_Aslam
author_rank: Contributor
timestamp: August 17, 2022, 06:58:32 am
content: In one of my projects, I need a circuit or EVM board that can provide me the customizable delay. Here customised delay means that I will connect my input to this ckt/board then according to the feedback(command) it should add the delay in my input signal and will give it on the output port.Suppose I am measuring the delay of two 1PPS signals and the output is 100ms, then that board should add the delay in the stop/start signal to down the delay from 100ms to say 100us and it should maintain this delay.So please suggest any Circuit/IC/EVM board which can do this task.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: August 17, 2022, 09:47:47 am
content: Accuracy of 100mks without problems should be provided even by a microcontroller. Those. any one you know will do. Microcontroller or FPGA. I think even arduino can be made to perform this task.

author: Md_Aslam
author_rank: Contributor
timestamp: August 18, 2022, 07:17:08 am
content: Quote from: MegaVolt on August 17, 2022, 09:47:47 amI want a stable delay and in microcontrollers like Arduino, the clock is not stable enough as it drifts more over the span of time. I think FPGA is a good idea but I Was looking for some already made evaluation boards or modules.

author: Ian.M
author_rank: Super Contributor
timestamp: August 18, 2022, 08:19:51 am
content: Arduinos are known for their crappy system oscillator accuracy - many of the older ones don't even have a crystal but use a ceramic resonator, and some use the internal oscillator, which is barely good enough to meet the lax requirements for baud rate accuracy for serial comms.Given an appropriate clean and stable clock source, MCUs and FPGAs will have very similar timing accuracy and stability. PLLing up an external clock to get a faster system clock uses similar silicon no matter whether its on a MCU die or a FPGA die, and the I/O drivers are remarkably similar.Grab any MCU you are familiar with and have the toolchain for that's fast enough that one cycle of it's max. I/O clock is fine enough granularity for your delay adjustment, clock it with a *GOOD* clock signal e.g. 10MHz from a GPSDO and if your code is correctly written, and the input clock signal is within spec. the output edge timing will be accurate to a small fraction of the input clock signal with the extra timing drift and jitter it contributes an order of magnitude smaller.

author: MrYakimovYA
author_rank: Regular Contributor
timestamp: August 18, 2022, 08:23:55 am
content: Quote from: Md_Aslam on August 18, 2022, 07:17:08 amHow does the clock drift relate to microcontoller? Take a stable OXCO/TXCO generator then.FPGA doesn't provides a stable clock by itself. If you take an ordinary crystall oscillator then you will have the same drift as with microcontoroller.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: August 18, 2022, 08:26:58 am
content: Timers in microcontrollers are very stable.But FPGA is also possible. In my opinion, almost any modern FPGA will do.If the old software suits, then Spartan 6https://aliexpress.com/item/32890953742.htmlIf new software is important then Artix 7 will be a bit more expensive.https://aliexpress.com/item/32691533741.html