Martin Wollatz

The example programs read with READ_ALL_AVAILABLE. For me, this meant that fragments of the 4-byte variables were also read. That's why I want to determine beforehand how many samples are in the buffer. However, the mcc172_a_in_scan_status function shows strange behavior. If it has not yet been read with mcc172_a_in_scan_read, mcc172_a_in_scan_status always reads a 0. Only when at least 1 value has been read will the number of values be displayed correctly. Am I doing something wrong? do { // Since the read_request_size is set to -1 (READ_ALL_AVAILABLE), this // function returns immediately with whatever samples are available (up // to user_buffer_size) and the timeout parameter is ignored. //////////////////////////////////////////////////////////////////////////////////////////////////////////////// result = mcc172_a_in_scan_status(address, &scan_status, &samples_to_read); STOP_ON_ERROR(result); printf("read %u status %i\r\n", samples_to_read, scan_status); if (samples_to_read == 0)samples_to_read=1; //if i don´t have this, nothing will be read at all... result = mcc172_a_in_scan_read(address, &read_status, samples_to_read, timeout, read_buf, user_buffer_size, &samples_read_per_channel); STOP_ON_ERROR(result); if (read_status & STATUS_HW_OVERRUN) { printf("\n\nHardware overrun\n"); break; } else if (read_status & STATUS_BUFFER_OVERRUN) { printf("\n\nBuffer overrun\n"); break; } total_samples_read += samples_read_per_channel; ... }

Thank You for the fast reply. I wanted to switch off the on-board clock on my MCC172 with SOURCE_SLAVE. I am familiar with the connection between clock and sampling rate in a delta sigma converter.

I would like to use an MCC172 with an accurate time base. An atomic clock (CSAC) is built into our devices, and I can divide the PLL out as desired. Is it correct that the GPIO19 can be used for this? At least there is a rectangle with 5.24MHz when I configure the MCC172 with SOURCE_MASTER.

I should have read all the manuals beforehand. Now I'm sitting with an RP5 that doesn't want to work with the MCC172. Or is there already an update to the library and I'm just too stupid to find it?

I bought an MCC172 and looked at the input circuitry. As I suspected, there is a high pass built in, but it is even equipped with jumpers to bypass the high pass capacitor. The component values, even if they are measured within the circuit, result almost exactly in the cutoff frequency specified in the data sheet. For DC coupling, simply close the jumper (circled in green). mcc172 analog.bmp

We have some applications where we need to record two channels. The MCC172 board is ideal here, but we rely on a DC coupling. Would it be possible to achieve DC coupling with this board? I'm hoping that only a high pass could be bridged in the analogue part. Since no schematic is shared it is impossible to determine.