Hi is any reason why the `make run` is running in ...
# mpw-2-silicon
i
Hi is any reason why the
make run
is running in 1,6V? can we go higher or is not recommended/make sense?
m
it's to work around the hold violations. But it's only needed for setting the IOs up, then it can be increased to the nominal 1.8v
i
I just if make sense to test if IO work for example between 1,3 and 1,8 for example. Is to have an automated test for the vest voltage.
t
@Ivan Rodriguez: It's best to calibrate the device and to power up the device at a voltage that produces the best outcomes. We ran a number of calibration attempts on different parts and concluded that we got the best calibration results at around 1.6V. Anecdotally, I have found, when testing an assortment of parts I have on my desk, that it works best to keep the voltage as low as possible without everything failing due to the low voltage, which is 1.43V (in the conversation just above, Matt Guthaus got better results at a little higher voltage, 1.45V, although that result might be part-dependent). Jeff just updated the code base yesterday to include a new routine that sets the voltage without powering down the system, so you can bring up the device at the voltage where it was calibrated, let it program the GPIOs at that voltage, and then you can change the voltage to whatever you want for testing.
i
thanks for the clarification, great to now, so the idea is to have the voltage as low as posible to reudce the hold vilations no?
t
It tends to help. The problem with hold violations is that they involve a race condition between two signals, and slowing things down by lowering the voltage can slow down both signals, so there's no guarantee that you don't make the violations worse by lowering the voltage. But at least for these violations that are causing the problems on MPW-two, making the supply voltage lower helps.
i
Thanks a lot for the information. Do have seen any big changes in the hold violation with different temperature? I will need to test them in some "extreme" environments, if my design happens to work. The temperature can fluctuate between +/- 10 ºC
m
Jeff just added the option to change the voltage after IO configuration: https://open-source-silicon.slack.com/archives/C03UVJCTR8U/p1676497949050559