| ??? 03/10/08 08:27 Read: times |
#152060 - Simplex Responding to: ???'s previous message |
Alan Dorman said:
The printer and LCD do not send any data back to the CPU. So you don't need to use the MCU's Rx input to the UART, then? So how about driving one device from the MCU's UART, and then bit-banging a serial output on the unused "Rx" pin? If a printer or LCD sees garbage would it try to print or display that garbage or would it simply ignore it because of the baud rate error? Who knows? And even if you try it and it "seems" to "work", how can you be sure that it will never get into some strange state due to the dodgy data...? You really don't want to go there... Some of the port pins are used to bit bang into a row of serial OC drivers and the other bit bangs into a EEPROM. Does the EEPROM use I2C or SPI? If it does, then why not just use an LCD with I2C or SPI interface? Or an I2C or SPI-connected UART? Or a "slave" micro to "roll-your-own" I2C-to-LCD driver? I could add another RS232 chip and some glue logic ... Would that idea work? Well, that's basically "multiplexing" it! You'd have to work out the fine detail of how to make it work with your existing stuff. But this is a non-trivial hardware change - would it not be simpler to just get a microcontroller with 2 serial ports?! |
