fullduplexserial.spin

El Paisa

Is in the Hydra software a program like fullduplexserial.spin?
I would like to comunicate with a serial device at 115200 baud.

Mike Green

Just use the routine in the Propeller library. There are no changes necessary. The system clock in the Hydra is the same (80MHz=10MHz*8) as that in the Demo Board (80MHZ=5MHz*16). Just be sure to pick appropriate pins to connect your device (some pins are used differently on the Hydra).

rokicki

Right, just in case anyone is trying to do this with the demo board, here's the magic incantations I found to work.

On the propeller side of things, this worked:

CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
OBJ
ser : "FullDuplexSerial"
PUB start | b
ser.start(31, 30, 0, 115200)
ser.str(string("I am alive", 13))
repeat
b := ser.rx
ser.tx(b)

(this is just a copy-data).

On the Windows side of things, I compiled the following
program from cygwin. (Cygwin is free and comes with a
C compiler).

I needed to do this because I'm testing my SD/FAT write
routines, and I want to run some intensive tests without
wearing out a card, so I'm doing the block I/O over serial
to a hard disk on my laptop. It's much slower, but it will
let me run many days worth of intensive testing.

Dennis Ferron

I think it's important to point out that serial communication will only work with a crystal clock. If you use the internal RC clock, you can't get enough timing accuracy for the serial duplex object to correctly guess when to sample the last 2 or 3 bits. The least significant bits will come out ok because the % of timing error accumulates throughout the receipt of the byte; at first there isn't enough error to matter but by the time you finish a byte the timing is too far off.

When debugging serial communications, I recommend making a loop that sends bytes with values 0, 1, 2, 3, ... up to 255 and then start over again. This is your best chance of at least receiving something even if it's wrong, and once you have a little bit going through you can start to sort out what makes it work better and what makes it stop working.

El Paisa

Mike,

You·were right, the only thing I changed was the clock settings and the pinouts.

I am using the fullduplexserial.spin

Now I can communicate with a ezLCD-004 Graphics display at 115200 baud.

Thanks again.

James Long

What are you using to communicate? The USB...or another connector.

James L

Post Edited (James Long) : 12/13/2006 5:11:14 AM GMT