Part Number: TMS320F28235 Hi, We faced one issue on F28235 GPIO24 as ECAP. GPIO24 is used as ECAP, to detect a falling edge and init an interrupt. Sometimes, the interrupt is not initiated. In details: 1) GPIO24 is external pullup by 10K resistor; 2) IGBT driver's fault signal (5V), goes to level IC (74xxxxx) and output 3.3V, it goes through 10 Ohm resistor to GPIO24. 1000pF is placed to GPIO24. 3) When no error from IGBT driver, the signal on GPIO24 is always high (3.3V); when IGBT driver's error happens, the signal changes from high to low, without return back to high. It means that, there's only one falling edge. It happened that, 5% ECAP interrupt can't be initiated. What test we did: 1) Connected with the emulator and use emulator to control the code's start/stop, every interrupt can be initiated. 2) Connected with emulator, but CCS is not connected with the device, still, ECAP interrupt can't be initiated in a low rate. 3) Disconnect the 10 Ohm, and place a PWM signal to GPIO24, every interrupt can be initiated. 4) GPIO24 sample window are changed, without any improvement. 5) The oscilloscope on GPIO24, is nearly the same on case 1) and 2). The falling edge is quite good. 6) Pin123 is used as an input GPIO. If place an external 3.3K pull-down, 100% the issue happened. 7) Through the CAN port, we see that, when the IGBT driver is OK, GPIO24 is high (GPADAT.bit.GPIO24==1). When driver is not OK, GPIO24 switches to low (GPADAT.bit.GPIO24==0). There's the switch from 1 to 0, when CAP interrupt can't be initiated. 8) We are quite sure that, there's no bug in the code. It works well. What could be the issue? Thanks a lot. Br, Jordan
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