Vermes
Advanced Member level 4
It is an USBasp programmer closed in housing of old PenDrive USB.
Assumptions:
- buffered outputs going into state of high impedance after saving/reading is complete
- handling of input signal levels 3,3V and 5V switched by a single switch
- possibility to program the programmer by the same connector (without the need to provide additional connector)
- reduced sensitivity to voltage spikes
The microcontroller is powered by a small resistor, behind it there is a 10uF capacitor, what quite effectively eliminates voltage fluctuations. Buffer goes into high impedance state without any problems, what is useful for programming systems which use SPI connector.
Pictures:
Link to original thread - USBasp - buforowany mini programator z napięciami 5V/3.3V