Summary: ECP5 SerDes Out-Of-Band Tx/Rx

serdes ecp5 out-of-band

This post is a summary of the findings from my look at using the ECP5 SerDes for USB3 LFPS for quick reference of how to use the ECP5 SerDes semi-documented out-of-band I/O features.

Quick summary:


To use this functionality, add the following to the invocation of the SerDES DCUA block, replacing CHX with your channel number:

name type description
CHX_LDR_RX2CORE_SEL parameter Set this to 1 to enable receiving out-of-band data; works in parallel with normal SerDes operation.
CHX_LDR_RX2CORE output When CHX_LDR_RX2CORE1_SEL is set, this carries input value from the SerDes Rx input. Captured post differential input, and thus is single-ended.
CHX_LDR_CORE2TX_SEL parameter Set this to 1 to drive the SerDes Tx output directly; remains in affect until overridden via a SerDes Client Interface register. You most likely want to leave this at 0.
CHX_FFC_LDR_CORE2TX_EN input When CHX_LDR_CORE2TX_SEL is 0, this controls whether the SerDes Tx output is driven by the SerDes (0) or by the CHX_LDR_CORE2TX signal (1).
CHX_LDR_CORE2TX input When this is enabled by either CHX_LDR_CORE2TX_SEL or CHX_FFC_LDR_CORE2TX_EN, the value provided to this signal is directly routed to the SerDes Tx output.


These descriptions are based on my initial experiments; and should be taken with a grain of salt. :)