Atmel ATMEGA328PB code for SmartParallel project.
This is a perpetual work in progress.
It requires a number of my libraries, so you'll need to ensure you set these up appropriately.
The main function of this code is to sit and wait for incoming messages on the serial port. It also sends updates and status messages as appropriate via serial to the host.
Messages sent from the SP board have one of three prefixes:
- SER_ for messages relating to the serial port/connection.
- PRT_ relating to printer functions/actions.
- PIF_ relating to printer interface settings or status.
Incoming messages are assumed to be one of two types:
- A command – to define a setting on the SmartParallel, ask for information about printer status etc.
- A line of text to print.
Either way, the message must be terminated with a null character (ASCII 0). If bytes are received on the serial port but no null terminator arrives within a given time, the program times out and dumps the characters received. Also, if the incoming buffer (255 bytes, including terminator) fills without having received a null byte, the final char is replaced with the null byte and we go with what we've got.
Commands are sent by making the first byte ASCII 1. Any incoming bytes where the first one isn't a 1 are assumed to be text to print.
Messages sent by the SmartParallel to the host during printing operations are:
- PRT_READY - the interface and printer are ready to print.
- PRT_DONE - the interface has sent a character to the printer without receiving an error.
- PRT_INIT - the interface is performing the printer initialisation function.
- PRT_OFFLINE - the printer is offline (the printer's SELECT line has gone low).
- PRT_PRINTING - the interface has sent text to the printer.
- PRT_BUSY - the printer is busy. This is in response to a BUSY signal from the printer.
- PRT_ERROR - the interface received an ERROR signal from the printer.
- PRT_PE - the interface received a PAPER OUT error from the printer.
- PRT_ACK_TIMEOUT - the interface timed out while waiting for an ACK signal from the printer.
- PRT_BUSY_TIMEOUT - having sent a character to the printer, the printer has been sending a 'busy' signal for a suspiciously long time, so an error has probably occurred.
If an LCD display is fitted, similar messages are sent to that.
Commands are sent by making the first byte ASCII 1. The next byte is the command.
Cmd Function (Dec) 1 PING - prompts the SP to send back the string SER_PONG. 2 DISABLE ACK - tell SP not to use the ACK signal when talking to printer. Responds with message: PIF_ACK_DISABLED 3 ENABLE ACK - tell SP to use the ACK signal when taling to printer. Responds with message: PIF_ACK_ENABLED 4 AUTOFEED DISABLE - turn off Autofeed on the printer. Responds with message: PIF_AF_DISABLED 5 AUTOFEED ENABLE - turn on Autofeed on the printer. Responds with message: PIF_AF_DISABLED 8 PRINT MODE NORMAL - set standard 80-column mode 9 PRINT MODE CONDENSED - set condesned 132-column mode 10 PRINT MODE DOUBLE - set enlarged 40-column mode 16 LINE END NORMAL - don't add anything to the lines of text received 17 LINE END LF - add linefeed (ASCII 10) to lines received 18 LINE FEED CR - add carriage return (ASCII 13) to lines received 19 LINE FEED CR-LF - add linefeed & carriage return to lines received 32 REPORT STATE - request status report on printer 33 REPORT ACK - request state of ACK/NO ACK setting. Responds with message: PIF_ACK_ENABLED or PIF_ACK_DISABLED 34 REPORT AF - request state of Autofeed setting. Responds with message: PIF_AF_ENABLED or PIF_AF_DISABLED