Parallel Flash Programmer Shield Preview

[Mike - K8LH]

Just wanted to preview a Flash Programmer Shield I'm working on to be able to program SST39 series 128K, 256K, and 512K Flash chips for my retro' computer projects. The boards turned out nice and I'm currently working on the Arduino software... Suggestions and/or criticism welcomed...

Stay safe. Happy Holidays and cheerful regards, Mike, K8LH

 

[Mike - K8LH]

I just discovered I can program 8/14/20 pin PICs using LVP on my little $5 Arduino Flash Programmer Shield. No hardware modifications required.

This is the first time I've tried to do LVP programming. I'm kinda' geeked!

Happy Holidays. Cheerful regards, Mike

 

[Nigel Goodwin]

I wonder what it would take to generate 8-9 volts for HVSP?

I don't know what modern devices require?, but certainly the older PIC's mostly need 13V in order to switch to programming mode - some devices suggested 12V, but 13V was always much more reliable.

The PICKIT 2/3/4 use a simple switch-mode circuit to generate the programming voltage, monitoring it's level via A2D and turning the switch-mode ON and OFF entirely to maintain the voltage within specified limits.

 

[Mike - K8LH]

I'd like to be able to program the more recent 9-volt 16F15xxx, 16F18xxx, 18FxxK42, and 18FxxQ43 devices but they require a relatively expensive PICKIT 4 programmer. I'm really geeked about the possibility of programming these chips with my $3 Arduino Uno clone and a custom $5 "PIC Project Programmer" board of my own design.

 

[Mike - K8LH]

If anyone is interested... I tested the 2-stage Dickson Charge Pump circuit last night and the output is adjustable up to about 12.7 volts. I'll hook up the ZIF socket and test HV programming next.

Regards, Mike

 

[Nigel Goodwin]

You might like to check the schematic of the PICKit 2 & 3, and see how they do it there - using a small inductor fed via PWM.

 

[Mike - K8LH]

You might like to check the schematic of the PICKit 2 & 3, and see how they do it there - using a small inductor fed via PWM.

I've studied those schematics and boost circuits in the past. Thank you for mentioning them. Honestly, I'm not sure I need anything that complicated. This charge pump circuit uses about 20¢ worth of relatively common parts and should fit nicely on a custom Arduino 'shield' along with a ZIF-20 and a ZIF-28 socket. I'm looking forward to some serious testing.

Happy Holidays. Mike

 

[Mike - K8LH]

A little premature but I thought I'd look at a sample PIC Project Programmer PCB layout for Arduino Nano... This example is 2.4" x 2.8" and cost is about $1... I ordered ZIF-20 sockets (70¢ each, landed) and ZIF-28 sockets (95¢ each, landed).

 

[Visitor]

Some ZIF sockets have rectangular tabs instead of pins that won't fit standard socket patterns.

 

[Mike - K8LH]

Some ZIF sockets have rectangular tabs instead of pins that won't fit standard socket patterns.

Yes, I'm aware of that, thank you. I'm using a hole size that allows the Chinese ZIF sockets to be press fit onto the board with slight pressure.

 

[Nigel Goodwin]

Yes, I'm aware of that, thank you. I'm using a hole size that allows the Chinese ZIF sockets to be press fit onto the board with slight pressure.

I had to drill mine out

I'd checked with a socket I'd already got, but (as Visitor says) when the Chinese ones came they had rectangular pins (my old socket had round pins) - you live and learn.

 

[Pommie]

I seem to be always forcing square pins into round holes!! Guess that's just how stuff works.

Mike.
BTW, could just be larger pins into smaller holes!!.

 

[Visitor]

I think I wrote about this some years ago, but it's still a helpful hint.

I routinely use ICSP for my PICs using a PICkit. I needed to bulk- program some 28 pins DIPs and although I have one of those universal adapter boards with various sizes of ZIF sockets somewhere, I couldn't find it.

The easy solution? I had some 28-pin bare boards with an ICSP socket that that were essentially scrap (wrong footprint for one of the other chips on the board that proved useless anyway). I soldered in the ZIF socket and a six-pin header, connected it to the PICkit with a short jumper and was in business.

 

[Mike - K8LH]

I've used solderless breadboards to connect to target chips in the past but you need to be very careful with the pinout...