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Topic: ATtiny85 programming hardware (Read 7 times) previous topic - next topic

Graynomad

Oct 12, 2010, 05:25 am Last Edit: Oct 12, 2010, 04:43 pm by graynomad Reason: 1
Hi all,

I'm about to go to PCB fab with a gadget to allow in-circuit programming of the ATtiny85 with full isolation of the programming pins including RESET for high-voltage programming.

Details here

http://www.robgray.com/emul8or/index.php

Schematic

http://www.robgray.com/emul8or/documentation/docs/emul8or-SCH.pdf

PCB layout

http://www.robgray.com/emul8or/graphics/pcb-2.png

Does anyone have thoughts on features or spot an error before I commit to having boards made.

Rob

NOTE: This is not a programmer it's an adaptor to isolate pins, it is designed to work with an existing programmer.
Rob Gray aka the GRAYnomad www.robgray.com

jabber

What have you done with the schematic?   it has gone  :)

Graynomad

Rob Gray aka the GRAYnomad www.robgray.com

Graynomad

In the "why didn't I think of that" category I had a suggestion over on AVR Freaks.

Use a larger chip with enough free pins to emulate the 85 while handling the the ISP programming as well.

The trouble is if you want to use the USI in the target application you are back to the same problem, ie sharing ISP pins with the programmer and you can't remap the USI function to different pins on AVR processors...or so I thought.

With the Tiny861 you can map the USI pins to another port while leaving the SPI functionality on the original pins, so it should be easy to design a small adapter board and write code with conditional blocks to run on either chip, 861 for developing ans 85 for application.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Graynomad

Thanks for the input, here's MK2.

Following from suggestion by one of the guys at AVRfreaks I'm using a Tiny 861, but if a single 861 is good then two has to be better right?

So this design has a controlling 861 that talks to the emulating chip and also an FTDI cable to a PC. This will allow IO for a monitor program.

Another pin on the emulating chip is brought out to a header to allow the application to trigger an LA or CRO.

Reset is handled by the controlling chip mostly to allow daisy-chaining of two or more emulators.

Mk2 does not allow for HV programming, just normal ISP.

New schematic

http://www.robgray.com/emul8or/documentation/docs/emul8orMkII-sch.pdf

I still might build Mk1 because it is a more geniune emulation, for example you can use AREF with Mk1 but that's not practical with Mk2, but MK2 has a lot more potential for debugging because it has links to the outside world to display data and trigger test equipment.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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