[Open Crypto Project] #48: AVR field upgrade

[Open Crypto Project]

#48: AVR field upgrade
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 Reporter:  pselkirk     |       Owner:
     Type:  enhancement  |      Status:  new
 Priority:  major        |   Milestone:  Alpha board DNSSEC signer
Component:  HAL          |     Version:
 Keywords:               |  Blocked By:
 Blocking:               |
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 For initial development, the AVR will be programmed through a 6-pin SPI
 header with a usbtiny programmer, but we would like to have a software-
 based upgrade path (PC -> ARM -> AVR).

 The ATtiny828 datasheet says

   The device provides a self-programming mechanism for downloading and
 uploading program code by the MCU itself. Self-Programming can use any
 available data interface and associated protocol to read code and write
 (program) that code into program memory.

 I think we can do this over I2C, using two of the 4 AVR_GPIO_ARM lines.
 The STM32 HAL includes I2C, which looks like it can be configured to
 arbitrary GPIOs. I haven't looked at the AVR libraries yet.

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Ticket URL: <https://trac.cryptech.is/ticket/48>
Open Crypto Project <https://wiki.cryptech.is/>