Hi all,
we have a board based on MSP430F5328 and we'd like to use a single RS232 port both for communication and bootstrap loading . That is, we use the MSP430F5328 together with an SBC and we'd like to share the same serial port on SBC for data communication with microcontroller and for firmware upgrade of the microcontroller code.
BSLTX (P1.1) and UART TXD (P3.3) can be paralleled together, as well as BSLRX(P1.2) and UART RXD (P3.4) ; this because at reset P3.3 and P3.4 are inputs by default so BSL communication can hold without problems; on the other hand, defining P1.1 and P1.2 as inputs in the firmware will lead to correct data exchange between SBC and microcontroller.
MSP430F5328 is a device with shared JTAG pins, so it uses RST/NMI and TEST pins for BSL sequence.
For BSL, these two pins can be driven by SBC through RS232 using respectively DTR (for driving RST/NMI) and RTS (for driving TEST) handshaking signals.
They are shared with JTAG interface.
For RST/NMI, some sort of wired OR using a FET can ensure that when using RST/ NMI for JTAG there will be no conflict due to the presence of DTR connection (programming DTR correctly by SBC)
For TEST, it's not needed actually for JTAG connection if we don't use alternative PJ signals : it can be tied to VCC using a pullup (which value?) , and then driven by RTS for BSL (again using a FET).
Is all correct?
Thank you, bye
