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Built-in USBtiny ISP

OpenSprinkler v1.2u and above have built-in USBtiny ISP programmer implemented using an ATtiny45 chip. USBtiny is one among many choices to directly program an AVR microcontroller, without the need of a bootloader. It is already supported by Arduino software. There are many implementations of USBtiny, notably Lady Ada’s USBtinyisp and SparkFun’s pocket AVR programmer. OpenSprinkler adopts the ATtiny45 implementation because it requires minimal components: one ATtiny45 and three resistors, that’s all. It makes use of ATtiny45’s internal PLL to avoid any external oscillator. In addition, OpenSprinkler uses slightly modified USBtiny code to maximize the data transfer speed.

3 Responses to “USBtiny Programmer based on ATtiny45”

  1. Michael says:

    Is your modified ATtiny45 code available for download? I am building a 1.02 board from scratch and have blank chips.

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