hserout and serial 7 segment display

[queenidog]

It doesn't say if it should be inverted or true mode.
I did try [hex bright,0] and other permutations, like sending the Ascii value "z" instead.

I finally put a scope on it and tried to relate the command to the scope trace. This is what I got for $7A (brightness control, Ascii "z")



When I write the binary version out, it is indeed $7A or %0111 1010, except it's back to front. What I would have expected to be the msb at the front end of the trace, is at the back end. In other words, what is being sent is not $7A, but %0101 1110. (At least when I used to demonstrate RS-232 signals, they used to follow that convention). Tell me if I'm wrong.

So, what do you guys figure is happening? Maybe the inverted/true mode business? How do I choose either mode? I was looking at the REV command to reverse all the bits, but that seems rather "kludgy".

The latest code:

DEFINE OSC 4                                                                                      
DEFINE HSER_RCSTA 80h ' Enable serial port (b7=1 to enable TX as serial port pins
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
define HSER_BAUD 9600                   
'DEFINE HSER_SPBRG 25  ' 9600 Baud @ 4MHz, 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically
trisc.6=0
LED var portc.6   
'****The following are the control codes for the Sparkfun serial 7-segment display
decpts con $77   ' "w"
bright con $7A   ' "z"
setbaud con $7F '2=9600, 4=19200
reset   con $76  ' "v"
lsb     con $7B  ' "{"
dig2    con $7C  ' "|"
dig3    con $7D  ' "}"
msb     con $7E  ' "~"


'hserout [setbaud,2]
Main:  
HSEROUT [bright, $ff]
       pause 50
goto main

[Dave]

I don't know where you ever thought that IEEE RS232 sent msb... They have been designing hardware USARTS with lsb for about 40+ years. You should Google RS232 protocol.... It's the LAW.....

[queenidog]

You're right, I'm an idiot. Of course it's lsb first. For some STUPID reason I was thinking the first bit was a STOP bit, not a START bit and got the whole thing wonky. It's been awhile since I've had to troubleshoot serial stuff.

Okay, now I've got it and it's even more perplexing that this doesn't work since the display is getting the right code. When I send out [$7A, $55], that's indeed what I see on the scope.

I think it's a timing issue and tried using DEFINE CHARACTER_PACING but that doesn't work either for values 1000 to 20000.

[Charlie]

Silly question, but have you tied the unused inputs appropriately? You may be getting noise resetting things or sending garbage on the SPI port...

[queenidog]

Unused inputs? You mean Rx? Are there more? The 16F887 is in the LabX1, all jumpers are in except the Tx, which I am using as an output.

[queenidog]

I figured what Charlie meant was unused SPI inputs on the display (which can use SPI or serial in). I tied the 3 inputs to ground, no change, then out of frustration (I had already thrown the display in the garbage...)I started hitting each pin with ground. After touching the RST (which I assume is reset), the display started working. No changes in code, and when I took off extraneous wires to the display (ie the 3 SPI inputs) and hooked it up in very basic mode with only SI, Vcc, and ground, it continued to work, even through power cycling and numerous downloads to the host chip (16F887). I can now display anything I want, anywhere I want.