AT90S2313-10PI - 20-pin ATMEL AVR ATtiny Microcontroller - This MCU is pin compatible with the ATTiny2313. Flash Program Memory: 2 kbytes, EEPROM Data Memory: 128 bytes, SRAM Data Memory: 128 bytes, I/O Pins: 15, Timers: One 8-bit / One 16-bit, PWM: 10-bit, Comparator: Analog Comparator, USI: Universal Serial Interface, USART: Full Duplex External Oscillator: up to 10MHz at 2.7 V and up to 20 Mhz at 5V. DATASHEET PDF: AT90S2313 Datasheet Minimal system The AT90S2313 is the predecessor of the ATTiny2313, it is almost the same but the AT90S2313 does not have an internal oscillator sacrificing two output pins. But the internal oscillator od the ATTiny2313 is very inacurate and will only do 8Mhz max so when you need precision timing or serial I/O I would always choose an internal oscillator. The chip is much cheaper than the ATTiny2313 and can do the same and can be ISP programmed as an ATTiny2313 configuration. PlatformIO configuration: [env:attiny2313] platform = atmelavr framework = arduino board = attiny2313 ; change microcontroller boardbuild.mcu = attiny2313 ; change MCU frequency boardbuild.fcpu = 8000000L uploadprotocol = custom uploadport = COM5 uploadspeed = 19200 uploadflags = -F -C ; use "tool-avrdude-megaavr" for the atmelmegaavr platform $PROJECTPACKAGESDIR/tool-avrdude/avrdude.conf -p 2313 -P $UPLOADPORT -b $UPLOADSPEED -c USBasp uploadcommand = avrdude $UPLOADFLAGS -U flash:w:$SOURCE:i Related pages https://www.heinpragt.nl/?p=2902