For my design I'm using io_analog[10:0], and io_clamp_low[2:1], and io_clamp_high[2:1] Looking here I've found the pin correspondence to the packaged chips: https://github.com/efabless/caravel_user_project_analog/blob/main/verilog/rtl/user_analog_project_wrapper.v From the comments, this looks good: io_analog[10:0] <---> mprj_io[24:14] However, I believe there is a typo for the io_clamp_high/low routing (line 96): /* Additional power supply ESD clamps, one per analog pad. The * high side should be connected to a 3.3-5.5V power supply. * The low side should be connected to ground. * * clamp_high[2:0] <---> mprj_io[20:18] * clamp_low[2:0] <---> mprj_io[20:18] * */ @User I assume this is not actually the case. Do you know what are the connections supposed to be here? Thanks!

Maybe the comments in

user_analog_proj_example.v

make this clearer?

Thanks for your response. It helps, but there is definitely something I am missing. Are all three signals (clamp_hi[0], clamp_lo[0], and io_analog[4]) shorted together on mprj_io[18]? I assumed there would be separate pins for each of these signals. Wouldn't clamp_hi and clamp_lo need to be driven at different voltages the same time for the clamp to work (not to mention using the io_analog[4])? Also referencing: https://caravel-harness.readthedocs.io/en/latest/pinout.html

The comment

clamp_high[2:0]   <--->  mprj_io[20:18]

was not intended to imply that these signals are connected, just that these signals are all associated with the same I/O pad. The indexes are different for different signals, which is why it is necessary to have a mapping at hand.

Ahh okay I think I see my confusion. I assumed there was a path from clamp_high/lo directly off-chip, but those are only connected internally (to some power rails). So the mprj_io[18] indicated on the wcsp pinout at this link is connected only to the internal io_analog[4], correct? the clamps_high/lo[0] are associated with that pad but are connected to only from the user project area? https://caravel-harness.readthedocs.io/en/latest/pinout.html

Yes, that's correct. If you decide to use one of those analog pads as a power supply, then you can (and should) protect it by connecting the clamp between the power net and ground, internal to your project area (but as close to the edge as you can make it). But you don't have to use the pad for a power connection, and if you need it for a signal you definitely do not want it attached to a clamp, which is why the clamp pins are by default left unconnected to anything.

Excellent. Thank you! It's all clear now.