A new brain for an old EPROM programmer? - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: April 28, 2019, 10:53:37 pm
content: I bought a 2nd hand standalone STAG EPROM programmer which was based on 6809E but otherwise is just analog goodness.. Various voltage supplies, constant current circuits etc... The logic is all 5V but otherwise quite straight forward.I would like to replace the 6809E with a more modern processor which has serial I/O and then write my own firmware (I can start with just a single EPROM type and don't need to support a wide range).I need to address quite a bit of I/O and to do this within reasonably tight tolerances e.g. a 50us programming pulse.My usual go to micro controller devices (PIC, AVR) are too small for my application...Any suggestions? A RPi with level translation? Something else that I could program nearer the bare metal to get the timing constraints right?

author: james_s
author_rank: Super Contributor
timestamp: April 28, 2019, 10:58:51 pm
content: What's the end goal of replacing the 6809? Does this device do something that a modern inexpensive programmer won't do? Unless you're just wanting a challenge, it seems like a big project when something like a GQ-4X is around $100 and there are much cheapr options like the TL866.

author: DDunfield
author_rank: Regular Contributor
timestamp: April 29, 2019, 02:53:40 am
content: Ahh.. memories. I published a 6809 based EPROM programmer design back in the 80's!Exactly how much I/O do you need?What about an STM32? Complete SOC available in many flavors with quite a bit of I/O.You can get an STM32F103 based "Blue Pill" board for ~$2. Search "STM32F103C8T" on Ebay.This presents a 40-pin DIP pinout most of which is I/O. Has 64k (officailly, 128k unofficially) flash and 20k RAM.ARM Cortex-M3 at 72Mhz should be able to handle your timing requirements with ease. Very easy to program at "bare metal", GCC based development tools abound.Dave

author: NivagSwerdna
author_rank: Super Contributor
timestamp: April 29, 2019, 07:48:21 am
content: Quote from: james_s on April 28, 2019, 10:58:51 pmI actually already additionally own a TL866. The goal is to take an industrial strength bit of hardware and drive it using something I can control easier.The 'new' unit is a bit rubbish in that it can only copy from the master socket to the slave socket(s) and has no I/O to a PC. I need to at least add the ability to send/receive images from the PC.This could be one of those 'a project too far' ideas... but it is worth considering.It is a Stag PP40, more details athttp://matthieu.benoit.free.fr/Stag_PP40_resources_page.htm.It looks like another possibility is hacking it into a PP42 but not sure how feasible that would be given I have a 40M100 personality for it.I have been looking for an excuse to look at STM controllers so maybe this is an opportunity (although obviously 5V is an issue).Conceptually the design isn't too hard... I have a keypad, a display, serial to PC, and some voltages to control. The programmer's voltage are controlled by three DACs with a bit of over-current protection logic (latch on fail).

author: NivagSwerdna
author_rank: Super Contributor
timestamp: April 29, 2019, 07:58:42 am
content: Quote from: DDunfield on April 29, 2019, 02:53:40 amIf I went... STM32F103... any suggestions on RAM interfacing? I really need at least an EPROMs worth and ideally a bit of head room. Given my programmer only has a 28 pin socket that limits the top range to some extent.Is there a slightly bigger STM32 with more RAM? 64K would probably do it.Perhaps a STM32F407 Discovery?

author: DDunfield
author_rank: Regular Contributor
timestamp: April 29, 2019, 09:57:31 am
content: Quote from: NivagSwerdna on April 29, 2019, 07:58:42 amI mentioned the "Blue Pill" just because it's so inexpensive, capable and easy to connect to. I use them for all kinds of "one of" projects.If you have a high-speed serial link to a PC and are only operating it from a PC, you can get by with less than an EPROMs worth or RAM, a 16k buffer would be easy.If you want to be able to do stand-alone copies etc. and need to buffer the whole device, then you could either use an SPI-RAM - I think microchip has some up to 1MB or so, or an STM32 with more SRAM. I'm using an STM32L476 with 128k in a project at the moment, but there are many other variants with larger SRAM. I think there's an F7 with 512k SRAM.Dave