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Topic: How to bootload/program an atmega328p at 1.8v (Read 2 times) previous topic - next topic

Jack Christensen

Adafruit's USBtinyISP programmer has a jumper to supply 5V to the target or not. When the jumper is not in place, no power is supplied, and the logic levels are shifted to match the target's supply. I've used one to program target boards operating at 3V and 3.3V, but not 1.8V, so I'm not 100% sure that it will work. I do think I'd stick to ICSP programming and forget the bootloader.

https://www.adafruit.com/products/46
http://www.ladyada.net/make/usbtinyisp/use.html

Quote
Jumper JP3 (USB power to target)

There's a jumper sticking out near the cables, JP3. When the jumper is in place (connecting the two wires) then that means that the USBtinyISP is providing 5V power to the device being programmed. If you don't want to power the device then just take the jumper out or make sure its only on one of the wires.

The USBtinyISP can only provide 5V, up to about 100mA to the device. If you need more power then you should remove the jumper and power the device seperately. (Alternately, if you're feeling adventurous you can reprogram the USBtinyISP to requires 500mA from the USB port instead of 100mA but if you dont know how to do this I'd suggest not)

Version 1.0 of USBtinyISP sends data to the device at 5V level no matter whether its powering the device or not so make sure its 5V compliant! (Note that there are 2 1.5K resistors in series with the data lines for protection)

Version 2.0 which is almost certainly what you've got, uses a level shifter so that if the jumper is not in place, it will use whatever the target voltage is, a lot better for your low-voltage devices!

So, if you have a device that needs to run at 3.3V or so, don't have the jumper in place!
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

philipm


I actually hadn't realised that ICSP programming (without a bootloader) would be so simple. I think I'll just get a AVRISP mkII. =)

Out of curiosity, if I stick to using the Arduino IDE, I'm assuming that the fuses are only set by the IDE when burning a bootloader. Is that right? (I.e. fuses are not set when using a programmer to load a sketch.)

CrossRoads

"using the Arduino IDE, I'm assuming that the fuses are only set by the IDE when burning a bootloader"  Correct. I have several boards with no FTDI header, only ICSP. I burn a bootloader first to set the fuses for normal 16 MHz operation, and then use File: Upload Using Programmer to  put a sketch on with no bootloader.  Biggest problem: forgetting the bootoader first and then getting reduced speed operation (1 MHz default).

MKii does not provide power, it senses the supply pin (6) and adjusts levels accordingly. Should work with 1.8V:

"•Programs both flash and EEPROM
•Supports fuses and lock bit programming
•Upgradeable for future device support
•Supports target voltages from 1.8V to 5.5V
•Adjustable ISP programming speed (50Hz to 8MHz SCK frequency)
•USB 2.0 compliant (full speed, 12Mbps)
•Powered from USB, does not require external power supply
•Target interface protection
•Short-circuit protection"
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

philipm

Perfect. I'm sure I'll forget the bootloader (or AVRStudio) to burn the fuses and end up scratching my head too. ;)

Thanks for all the replies.

CrossRoads

It usually happens to me to when I have not programmed in a while- then I waste a couple hours looking things over and writing simpler test code until I finally realize it is running too slow, and slowly dawns on me that fuses are not burned.  Usually late at night since I do most of my stuff then.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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