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Using serial line as "busy" line on SX (change to Inkjet driver code) — Parallax Forums

Using serial line as "busy" line on SX (change to Inkjet driver code)

ZootZoot Posts: 2,227
edited 2008-01-16 18:13 in General Discussion
I am thinking about making one of two (mutally exclusive) changes to the attached SX/B driver applicatino for the Serial Inkjet Board.

I've got the board on a Boe-bot with a BS2, and I want a way to either share a serial line with a servo controller, or get a better "busy" signal from the inkjet board when it is printing (so I don't have to time moves on the boe-bot -- sort of like busy pin on the Emic).

The former is easy enough, I think -- I'll add a required header address that must be received before accepting a command or start of string, (e.g. the serial stream would be "!IJ" followed by regular inkjet commands/string). This would also let me create an add'l command that would just send the prompt, so that the host could just send "!IJP" and expect a something back. A timeout would mean the inkjet is busy.

On the latter, (which I prefer, because I have the pins to spare and sending a serout and waiting for the timeout consumes precious time and space on a BS2), my thought was to have the SX drive it's serIO pin LOW whenever it is printing. Since the serial is open true, and the line isn't shared. I think this would work?

- host serouts usual inkjet data, e.g. STX, "text", ETX
- host then makes serIO an input
- inkjet SX holds it's serIO pin LOW during printing; HIGH when done (isn't this the TX IDLE STATE ANYWAY?)
- host sees input on serio has gone high, free to send serial data again

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When the going gets weird, the weird turn pro. -- HST

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