Micro with 100Base-T and TCP/IP stack suggestions please - Page 1
Forum section: electronics / general

author: deephaven
author_rank: Frequent Contributor
timestamp: January 25, 2016, 09:39:32 pm
content: I have an existing product which has a Renesas microcontroller on it which has an external 8 bit bus interface. I'm looking for a 100Base-T solution which would probably be another micro (not necessarily Renesas) with a ready-made TCP/IP stack available for it. I don't want to put the TCP/IP on the existing micro because I don't want it to have to handle the extra workload.Looking around, there seem to be plenty of vendors that do what I want, but I would be interested to hear from anyone who has done something similar so as to hopefully pre-empt any nasty surprises.

author: nctnico
author_rank: Super Contributor
timestamp: January 25, 2016, 10:31:29 pm
content: I not used the Wiznet chips yet but the latest models look like a good choice. Just make sure you read the datasheet carefully, decouple it properly and have a means to power cycle it from the MCU. I have gone the uIP route before but that needed lots of debugging.

author: deephaven
author_rank: Frequent Contributor
timestamp: January 26, 2016, 08:58:32 am
content: Quote from: nctnico on January 25, 2016, 10:31:29 pmThe Wiznet 7500 looks interesting with it's 'hardwired' TCP/IP stack and ARM processor. A bit concerned about availability as there doesn't appear to be a distributor with stock but it looks like you can buy them straight from Wiznet.I looked at the FTDI FT906. Their website has a refreshingly straightforward access to all the docs and tools.I use the Microchip parts for other projects, but nervous about using them for this as there always seems to be reports of bugs and peculiarities with them as if life isn't hard enough already!

author: nctnico
author_rank: Super Contributor
timestamp: January 26, 2016, 10:55:21 am
content: I have not read many positive things about that Wiznet 7500. The 5000 series (IIRC5500 is the latest) is stocked by Digikey, Mouser, etc and seems to be a design which went through several improvements.

author: deephaven
author_rank: Frequent Contributor
timestamp: January 26, 2016, 11:14:58 am
content: Quote from: nctnico on January 26, 2016, 10:55:21 amThanks for the comments. the W5500 only has an SPI interface, although it is fairly high speed, it won't be fast enough for what I need.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 26, 2016, 12:58:37 pm
content: What sort of BW do you need?Really what I wonder is do you really need 100BT?

author: nctnico
author_rank: Super Contributor
timestamp: January 26, 2016, 01:23:20 pm
content: It also depends on whether you can get away with using UDP only. TCP/IP is cumbersome to use for machine to machine communication because of it's long time-outs and you'll have to implement error/handling and retransmit on a higher level anyway. Additionally UDP is about 1000 times simpler to implement than TCP/IP.

author: deephaven
author_rank: Frequent Contributor
timestamp: January 26, 2016, 01:48:24 pm
content: I need the bandwidth, in fact 100 might not be enough. Thanks for comments on UDP, I'll see what the implications are.I'm gradually wondering if it is practical to do what I want. I may go for a Windows Embedded unit and sidestep the necessity of having so much 'live' bandwidth.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 27, 2016, 03:50:20 am
content: Quote from: deephaven on January 26, 2016, 01:48:24 pmWow! You need to sustain that for how long? What else is the software doing? I would be interested in hearing what you are trying to do. Just on a high level.

author: deephaven
author_rank: Frequent Contributor
timestamp: January 27, 2016, 09:39:23 am
content: Quote from: joeqsmith on January 27, 2016, 03:50:20 amI need to keep a display updated with live data. I'm already using propriety compression but, even with that, it needs to have a sustained rate of the order of 10's MB/s. So I'm beginning to think that this isn't achievable with my initial scheme. If I go for the second scheme of having the data hosted on a local small Windows board, it can buffer up the whole lot and take away the requirement of having so much 'live' bandwidth.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 27, 2016, 09:41:57 am
content: Raspberry Pi?

author: nctnico
author_rank: Super Contributor
timestamp: January 27, 2016, 10:29:57 am
content: Quote from: deephaven on January 27, 2016, 09:39:23 amDid you look into using FPGAs and a gigabit phy? Still I wonder about the display update rate. IMHO there is not much use to send 50fps over a network link when 5 updates per second are enough.

author: deephaven
author_rank: Frequent Contributor
timestamp: January 27, 2016, 10:57:06 am
content: Quote from: mikeselectricstuff on January 27, 2016, 09:41:57 amIt has to run software that we already have written for Windows.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 27, 2016, 11:46:27 am
content: How much of the CPU is currently utilized? Are you planning to write your own stack or do they offer this?

author: deephaven
author_rank: Frequent Contributor
timestamp: January 27, 2016, 01:18:53 pm
content: Quote from: joeqsmith on January 27, 2016, 11:46:27 amWell, as I said, I'm moving to a different solution with using a Windows board which has all that stuff solved.