Just inverting logic level and sending to a pc rs232 port may not work because some rs232 ports want higher level than 3 volts for data.
Raspberry Pi Serial Port Uart Chip Software On TheSo in my board, I have a PIC16LF1527 with TX1RX1 wired directly to TXRX on the Raspberry Pi (pic running on 3V from RPi) I have software on the RPi (supposedly proven to work) for driving the UART to talk to the PIC.In the debugger, when the RPi sends a byte, one of two things happens: - If the byte is anything other than null (0), then the PIC never sees it.If the byte is null0, then the PIC sees it, and triggers correct breakpoints in my debugger.
Been a while since I wrote a UART handler in a PIC, so maybe Ive just gone braindead. ![]() Notesclarifications: - Both PIC and RPi configured for 19200 baud - I was doing interrupt driven UART, but was having some trouble with it, so Ive switched off the interrupt, and am simply calling the interrupt function to poll the flags in my main loop. I can likely safely turn ints back on at this point) - The problem is below in the rxhandler. I have a breakpoint where I assign uartcmd RC1REG; and at that point, or the line after, Im seeing the above described behavior. The syndrome you describe might be explained if the active levels are opposite. Probably not what you want. Theres no UART receive error handling that I can see in the code. Need that stuff. - Whats supposed to happen in uartrxhandler() when the state is UARTBUSY. In state UARTIDLE its waiting on a command UARTCMD a command has been sent. IF that command expects a parameter byte, it stays in UARTCMD if not it jumps to UARTBUSY If in UARTCMD and a byte comes in it goes into the uartdata value (parameter byte) and then state changes to UARTBUSY. Yeah I should write some UART error routines, but this was just my first pass of the UART code, just wanted to get it working for a basic Hello World case (send a byte to the pic, have it respond with a string). Id agree with the earlier guesses that your data is inverted. The Rasberry Pi is probably running inverted data for connection to a PC, but your PIC is running true data if you are not using an RS232 buffer. The PIC does have a bit to invert the TX signal in hardware, but you would have to invert the RX signal with an external buffer if this is the case. To get a useful answer, always state which PIC you are using. Raspberry Pi Serial Port Uart Chip Driver You CanBesides generating the EUSART driver you can quickly set up the part and other peripherals. Thats not going to help much if the hardware is working with an inverted signal. Paging Dr. Susie Dr. Susie STAT Its a 16LF1527.with no other peripheral functions on his TX1 pins If he cant read the Data Sheet and get the freakin EUSART going then hes going have loads of fun later on.and be right back here asking questions. No amount of hiding behind some silly candy-wrapper software is going to save him then. You guys need to focus on: - continuing to make really cool chips - pulling your head out of some corporate bean-counters a and make the fully-optimizing compilers free (so you can sell lots of those really cool chips - that is your business model anyway, right) - making MPLAB X less of a steaming pile. So all of this implies that the UART on the Raspberry Pi is using 3.3v 1 and 0v 0 on its UART.
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