Erasing Microchip ATF series CPLD after setting security fuse - possible? - Page 1
Forum section: electronics / general

author: deanclaxton
author_rank: Regular Contributor
timestamp: September 05, 2020, 07:28:45 am
content: I'd like to know if there is a way to erase an ATF1500 series CPLD after setting the security fuse.Is there a method similar to the 12V OE1 trick used to re-enable ISP if JTAG pins are used for IO? This doesn't appear work if the security fuse is set.

author: deanclaxton
author_rank: Regular Contributor
timestamp: September 05, 2020, 08:54:24 am
content: Some more info on these chips here :https://www.eevblog.com/forum/fpga/atmel-atf150x-cpld-and-wincupl/I just need to find out whether it's possible to recover a chip with the security fuse set without removing the chip from the board and using some $$$$ programmer.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 05, 2020, 09:22:03 am
content: I've never come across any reprogrammable chip that can't be erased after securing.I'd think there would be a warning in the datasheet if it was not possible, though if there are multiple programming methods there may be some limitations.

author: deanclaxton
author_rank: Regular Contributor
timestamp: September 05, 2020, 11:19:46 am
content: yeah - I'd like to be able to erase and re-program the device after securing it. I'm sure there would be a method - just can't find any info out there on how to do it

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 05, 2020, 02:04:23 pm
content: Quote from: CJay on September 05, 2020, 10:30:02 am

author: NorthGuy
author_rank: Super Contributor
timestamp: September 05, 2020, 04:11:20 pm
content: Quote from: mikeselectricstuff on September 05, 2020, 09:22:03 amNewest Microchip PIC24s have security setting which prevents external erase/re-programming completely. So, this is certainly possible.

author: up8051
author_rank: Frequent Contributor
timestamp: September 05, 2020, 06:29:25 pm
content: My parallel programmer Labtool48 support this chip and has option Erase, but I haven't any ATF15xx to test erase after secure.

author: deanclaxton
author_rank: Regular Contributor
timestamp: September 06, 2020, 08:08:03 am
content: Quote from: up8051 on September 05, 2020, 06:29:25 pmIs there any way to view the programming algorithms? It would be very interesting to see which pins its using, and what voltages are applied (assuming the erase actually erases a chip with security fuse set).

author: TomS_
author_rank: Frequent Contributor
timestamp: September 21, 2020, 11:31:03 am
content: I suppose you could hook up an oscilloscope to a bunch of pins, capture the waveforms, and reverse engineer it from there.I believe that is part of the process people on this forum used to reverse engineer the programming algorithm for the Padauk microcontrollers and build a programmer for them.Ive got a scope, but would just need access to a programmer.

author: David Hess
author_rank: Super Contributor
timestamp: September 22, 2020, 07:36:59 pm
content: If these are EPROM based, then they can be erased using x-rays instead of ultraviolet to get past the packaging and security.