@rjo we got the bitstream built and successfully flashed the device but are still unable to use set_group(). We tried following the code from this post exactly, but did not see our DAC channels update with the expected voltages. We have confirmed that we are able to communicate with the DAC card by using set_leds(), and we know the DAC channels themselves are not destroyed because, when we roll back to the previous firmware (log2_width = 0), we are able to set the DAC channels in a loop using set_dac(). With the new firmware (log2_width = 5) we do not get any results. We're not sure whether this or not this is still a firmware issue. Any advice as to how to proceed?