> -----Original Message----- > From: uclinux-dev-boun...@uclinux.org [mailto:uclinux-dev- > boun...@uclinux.org] On Behalf Of Fabio Giovagnini > Sent: Thursday, April 01, 2010 12:37 PM > To: uclinux-dev@uclinux.org > Subject: [uClinux-dev] Does any of you made an rs485 driver starting > from uart? > > Hi all, > I have the following problem: > I' have connected my SCIF1 port (of sh2a 7203) to a MAX485, and the > TXEn/!RxEn to an I/O port. > I had the idea to write a driver for proc FS to manage the TxEn/!RxEn > line and > using the ttySCx driver to send and receive data at 38400. > But I need to wait the end of the last byte trasmission before to set > low the > TxEn/!RxEn line. > Now I'm doing it with a dilay time; but I was looking for a more > elegent > solution > > Any suggestion for me? >
I modified the 8250 driver for my board. I noticed that the serial8250_console_write function simply waits for the transmitter shift register to be empty before re-enabling the interrupts and unlocking a spin lock. I added some similar code to the __stop_tx function. This gets called when a transmitter empty interrupt occurs and there's nothing else to send. I just wait for the shift register to be empty and then clear the RS485 TXEn pin. Very ugly but I didn't have a hardware way to do this and I want to enable the receiver as soon as I can. Gary _______________________________________________ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
