Educating a USBasp Programmer to Talk TPI

Closing Fall [Kevin] sought after to program some more recent TPI-only AVRs the use of an outdated USBasp he had kicking round his lab. Discovering an “strange famine of data” and “boards full of mistaken data and schematics”, he made up our minds to set the file immediately and record issues as it should be. He sleuthed out the main points and succeeded in reprogramming the USBasp, even supposing he did finally end up purchasing a 2d one within the procedure.(*11*)

Designers who use AVR microcontrollers haven’t any scarcity of programming interfaces — we rely no less than five other strategies: ISP/SPI, JTAG, TPI, PDI, and UPDI. We’re no longer certain whether or not that is selection is just right or unhealthy, however it’s what it’s. [Kevin] discovers that for the specific circle of relatives of Attiny gadgets he’s the use of, the ATtiny20, TPI is your best option to be had.(*11*)

Whilst he typically builds his designs round ARM Cortex-M chips, [Kevin] wanted some glue good judgment and made up our minds to move with an ATtiny20 in spite of its distinctive programming necessities. He observes that the cost of the ATtiny20, $0.53 closing Fall, was once less expensive than the identical good judgment gates he wanted. This actual chip could also be moderately small — solely 3 mm sq. (a 20-pin VQFN). We would like to not use other MCUs and gear chains on a unmarried board, however from time to time the ease and economics steer the design in that path.(*11*)

Should you’re no longer accustomed to the USBasp, our personal [Mike Szczys] lined (*3*)the breaking tale over ten years in the past. And in case you have a large number of loose time to your fingers, ditch a majority of these properly packaged answers and program your chips the use of an outdated USB Hub and a 74HCT00 NAND gate as described on this unusual Mod by means of Teensy developer [Paul Stoffregen].(*11*)