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Serial Modem Communication — Parallax Forums

Serial Modem Communication

TrevorTrevor Posts: 8
edited 2007-02-23 04:31 in Propeller 1
I am currently working on a project that involves a family of autonomous vehicles. Our unmanned ground vehicle is currently using the propeller in conjunction with several other sensors including GPS, digital compass, ultrasonic, video, thermal and other components including MaxStream 9xStream serial radio modems.

The MaxStream RF modems interface via a DB-9 serial connection, so I therefore attempted to build a serial communication interface to allow the modem to communicate with the propeller. I built my interface off of a Maxim MAX3232 serial transciever in the same fashion as the PropStick serial interface, however as I need the circuit for communication rather than programming omitted the transistor circuit off of R1OUT in the attached schematic. I also am using general purpose pins rather than pins A31 & A30 as in the schematic.

However, after some experimentation I have so far been unable to transmit serial ASCII data over my RF modem and am unsure as to if my interface circuit is actually performing correctly. My code test code is very simple, yet I am rather new to Spin so it too of course could be to blame.

CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000

OBJ
TestSerial : "FullDuplexSerial"

Pub TestS
testserial.start(-1, 0, 2, 9600)
testserial.str(string("Testing 1,2,3"))



I am unsure if anyone else out there has tried something similar to transmitting serial data from the propeller to an RF modem and could give me any hints or suggestions.
975 x 549 - 26K

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