Part Number: DAC8742HEVM Other Parts Discussed in Thread: DAC8742H Tool/software: I am using two DAC8742HEVM to develop HART communication in which one serves as transmitter and the other serves as receiver. The transmitter board's MOD OUT is connected to the receiver board's MOD IN. Both boards use UART mode to interface with the controller board which is F28069M launchxl board. That is, one of the SCI ports of the F28069M is used to TX/RX data to/from the DAC8742HEVM boards. The controller (F28069M) is connected to both DAC8742H board through their J6 connectors directly. First of all, following the DAC8742HEVM user guide, I set up all jumpers for HART/UART mode. I connect the controller (F28069M) TX to the UART_IN of the transmitter DAC8742 board through J6. The /RST pin is pulled high constantly. A GPIO pin of the F28069M is used as /RTS signal and is connected to the /RTS pin of J6. I can successfully send data to the DAC8742H transmitter board as the red trace in the digital panel shown at 1200 baud rate: The red trace in the analog panel shows the HART signal for the input UART data. A measurement shows that the HART carrier (at the beginning of the HART signal stream) is 1196Hz (836us period), very close to the 1200Hz nominal frequency: For the receiver DAC8742H board, the /RTS is constantly pulled high to activate the demodulator for reception. For HART TX timing, the time delay between /RTS low to UART_IN starts sending data is 1ms-2ms (different delay values has been tried). However, the receiver DAC8742H board's CD pin is constantly low without toggling high for its MOD IN's HART signal. That means it does not recognize the HART carrier present at its MOD IN pin. The receiver board is set up with its bandpass filter on, using internal reference. Both the TX and RX DAC8742H boards share same power and ground with the F28069M controller board. Any advice for what would be the problem? Thanks and Best regards, William
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