OCDAC #

Brief #

ocdac sets the F3 hardware overcurrent comparator threshold hv0.dac from a trip current in A peak, using a linear map fitted per board. It runs on the F4 board and is loaded by conf/template/ocdac.txt with hv0.dac = ocdac0.dac and ocdac0.cur = 20. Use iddac (id_dac template) to find the dac for one current on a given board.

Component Explanation #

1. Dac map (nrt):

k       = MAX(k, 0.1);
dac     = CLAMP(roundf(dac0 + k * MAX(cur, 0)), dac_min, dac_max);
cur_out = (dac - dac0) / k;

• cur_out shows when dac_min or dac_max limited the result.

2. Calibration:

• The comparators see the raw shunt node (2.9 mV/A, about 3.6 counts/A in theory); the measured slope and offset depend on the TIM8 break filter, because the shorter filters trip on switching ringing on top of the current.
• Measured with filter 0xC (the default, periph.c), highest trip of the 60/180/300 deg angles:

• The defaults are X’s. Fit dac0 and k per board from a few trips (iddac finds the dac for one current directly) and save them in the config.

The map is a bench fit for one board and break filter setting; check it on your hardware before relying on it as overcurrent protection.

Pins #

References #

Source: .c File