7 Replies Latest reply on Apr 5, 2015 2:26 PM by jota_1939431

    How to just use TTL puart in TAG3 without through USB?

      I have read MMP920737TAG03-HWUM100-R.pdf, I know that TAG3 have a USB port and it can simulate two com ports on PC, one is HCI, the other is puart.

      Through USB, HCI and PUART work fine. But I have an idea that use PUART TX and RX pins which are TTL level. After checking the MMP920737TAG03-HWUM100-R.pdf, on GPIO header, I found that J7 Pin 5 and J8 Pin 1 are PUART TX and RX. I also found that I should switch SW4 pos5~6 to OFF to make PUART disconnect with USB module. Then, I use my TTL2USB cable to connect with J7 pin5 and J8 pin 1, but I can't get anything through tera term4.83. But after switch SW4 pos5~6 to ON, I can data output and input work normal through USB port.

      So, what extra action should be taken if I want to use PUART pin32 and pin33 which do not connect with USB port?

      BTW, my TTL2USB cable is this one: http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm