Electronic – In-place programming of ATtiny85

attinyattiny85isp

I've been playing around with an idea for a little hand-held gaming device using a Nokia 5110 screen and an ATtiny85.

The ATtiny is programmed using my Genuino UNO as ISP.

I was wondering if it's possible/sensible to include a breakout connector on the attiny pins so I can just plug it in whenever I want to update the code, rather than having to remove it from the gaming device? I'm worried about how signals from the ISP would interfere with the other devices connected?

I used Fritzing for the very first time to create a diagram of what I'm thinking of so far (I've breadboarded parts of it with the UNO instead of the ATtiny, and I haven't actually tested sharing the clock & data pins with the 3 controllers yet! The real thing would have more buttons and LEDs!)

Best Answer

Yes, it is very common to put a 6-pin ISP header on your board to allow the AVR to be reprogrammed in place. Even the Arduino has one of these on it.

Here is a nice application note from Atmel describing the typical pinout of the header along with some suggestions on how to make sure there will not be conflicts with the normal operation of the programming pins...

http://www.atmel.com/images/doc0943.pdf

If you plan on mass producing the board, you can even avoid needing the header by using this handy connector...

http://dangerousprototypes.com/2012/12/10/isptouch-header-less-isp-connector-for-avrs/

...or this one...

http://www.tag-connect.com/

Finally, you can connect directly to the chip itself using a chip clip like this ...

http://www.amazon.com/8-Pin-Gold-Plated-SOIC-Spacing/dp/B00DDE7N3C

Related Solutions

Electronic – AVRISP mkII not reading device signature

There are several possible problems. One is actually udev. If it runs fine calling avrdude with sudo, you have to get your udev stuff right. In Debian Wheezy I have the following line in my /etc/udev/rules.d/56-avr.rules file:

# Atmel AVR ISP mkII
SUBSYSTEM=="usb", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2104", GROUP="users", MODE="0660"

I guess you can change any appropriate group.

If that's not your error, check your circuit. A common problem is other things are connected to the ISP pin header. If you want to be sure, put the controller somewhere, where nothing else is connected to these pins and try to flash it there.

And finally: check the colors of the LED in the mkII. Errors or warnings are indicated by yellow/orange or red color. If everything is wired up correctly, the LED in the programmer is green.

Electronic – How much current is a powered-down ATtiny84 supposed to take

This comment on reddit pointed me to this page, which says that clearing the ADEN bit in ADCSRA shed as many µA as are currently in excess in my test rigs. I am away from the lab right now, but when I get home tonight, that's the first thing I'll try. I'm optimistic. I do know that the ADEN bit gets set in init() in wiring.c...

If it's confirmed, then the lesson is that PRR is not enough to turn the ADC all the way off.

EDIT: It is confirmed. The one added caveat is that order matters. ADCSRA must be written before PRR.

My sleep_tiny_sleep sketch (last above) now takes < 100 nA.

Best Answer

Related Solutions

Electronic – AVRISP mkII not reading device signature

Electronic – How much current is a powered-down ATtiny84 supposed to take

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