DIY EHCI debug dongle

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Hardware

A dongle to debug target with EHCI Debug Port capability can be built using two Cypress CY7C68013A (aka FX2LP) USB device chips. Theory of operation is described in Cypress Application Note AN63787[1].

There are a few boards in the 10-15 EUR pricerange to choose from and a dozen suppliers in ebay.

A slower uni-directional boot console has been demonstrated to work with one FX2LP and a TTL-UART-to-USB adapter. In theory at least, some JTAG dongles with FX2LP could be used to capture coreboot console from EHCI debug port.

Prototype

LCSoft FX2LP

LCSoft LCSoft

Schematics for prototype board and required modification.


Firmware

Firmware is built with sdcc using fx2lib.

Original git repository [2]. Offline.

Recent updates are here [3].