Simple Serial question
I am trying to rec'v serial commands from an external device. This device can't be changed.
What I am trying to do is control a LCD projector.
There are only four commands:
On
Off
RGB input
Video input
The On and Off commands are six bytes long and the RGB and Video are 8 bytes long.
All that is being done is the input to the BS2 is reading what button was pressed.
The baud is 38400.
With the Serin command I have setup an array of 8 bytes so when you press the 8 byte button it works great but when a 6 byte button is pressed the last two bytes don't get filled so the command waits. If I put a timeout in the command then some data may be missed completely when the code exits the Serin.
Just to explain this another way!
My input string is:
02 00 00 00 00 02 'On cmd'
02 01 00 00 00 03 'Off cmd'
02 03 00 00 02 01 01 09 'RGB input'
02 03 00 00 02 01 06 0E 'Video input'
These come in at 38400 baud.
A user can press any button at any time.
I need to see the string and determine what button was pressed then do my task according to the button pressed.
The problem I can't seem to get around is the fact that one string is 6 bytes and the other is eight.
The code I wrote so far is short:
bytearray var byte(8)
Main:
SERIN 14, 6, [noparse][[/noparse]STR bytearray\8]
DEBUG ? bytearray(0)
DEBUG ? bytearray(1)
DEBUG ? bytearray(2)
DEBUG ? bytearray(3)
DEBUG ? bytearray(4)
DEBUG ? bytearray(5)
DEBUG ? bytearray(6)
DEBUG ? bytearray(7),CR
goto Main
end
Any help would be appreciated.
Thank you,
Steve
What I am trying to do is control a LCD projector.
There are only four commands:
On
Off
RGB input
Video input
The On and Off commands are six bytes long and the RGB and Video are 8 bytes long.
All that is being done is the input to the BS2 is reading what button was pressed.
The baud is 38400.
With the Serin command I have setup an array of 8 bytes so when you press the 8 byte button it works great but when a 6 byte button is pressed the last two bytes don't get filled so the command waits. If I put a timeout in the command then some data may be missed completely when the code exits the Serin.
Just to explain this another way!
My input string is:
02 00 00 00 00 02 'On cmd'
02 01 00 00 00 03 'Off cmd'
02 03 00 00 02 01 01 09 'RGB input'
02 03 00 00 02 01 06 0E 'Video input'
These come in at 38400 baud.
A user can press any button at any time.
I need to see the string and determine what button was pressed then do my task according to the button pressed.
The problem I can't seem to get around is the fact that one string is 6 bytes and the other is eight.
The code I wrote so far is short:
bytearray var byte(8)
Main:
SERIN 14, 6, [noparse][[/noparse]STR bytearray\8]
DEBUG ? bytearray(0)
DEBUG ? bytearray(1)
DEBUG ? bytearray(2)
DEBUG ? bytearray(3)
DEBUG ? bytearray(4)
DEBUG ? bytearray(5)
DEBUG ? bytearray(6)
DEBUG ? bytearray(7),CR
goto Main
end
Any help would be appreciated.
Thank you,
Steve
Comments
Maybe your timeout is too long or too short.
Are the codes repeated as long as the user holds the button ?
Bean.
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Cheap used 4-digit LED display with driver IC·www.hc4led.com
Low power SD Data Logger www.sddatalogger.com
SX-Video Display Modules www.sxvm.com
Don't mistake experience for intelligence. And vis-vera.
·
The problem is, if you put in a timeout, the person could 'press the button' just before the timeout expires. So the SERIN gets one or two bytes, then times-out.
If you don't put in a timeout, the SERIN can sit there FOREVER waiting for the bytes -- it never leaves the SERIN, so never misses any bytes.
Sounds like it's time for a nice, small serial-recieve coprocessor like the:
http://www.rhombus-tek.com/co-processors.html
Use the "Simple Multi-Tasking" module -- gives you a serial input buffer.· Not bad for $12 plus shipping.
Do the strings end with either a CR or LF? If they do, you can tell the SERIN command to watch for the CR or LF. That way, you set up your SERIN to always want 8 bytes, but if the the CR or LF is seen, it fills the last two bytes with nuls.
I think the process is described in the helpfile related to SERIN.
Cheers
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Tom Sisk
http://www.siskconsult.com
·
There are no CR's or LF's at the end of the string.
Does anyone think the faster Stamp would correct this issue?
Just for FYI I will post the code that I just tried.
**********************************************************************
bytearray6 VAR Byte(6)
bytearray1 VAR Byte
DEBUG "Started", CR
Main:
SERIN 14, 6, [noparse][[/noparse]STR bytearray6\6]
SERIN 14, 6, 1000, debugit, [noparse][[/noparse]bytearray1]
debugit:
DEBUG ? bytearray6(0)
DEBUG ? bytearray6(1)
DEBUG ? bytearray6(2)
DEBUG ? bytearray6(3)
DEBUG ? bytearray6(4)
DEBUG ? bytearray6(5)
DEBUG ? bytearray1
'DEBUG ? bytearray(7),CR
GOTO Main
***********************************************************************
Main: ' wait for header
char = RX_BYTE
IF char <> "!" THEN Main
char = RX_BYTE
IF char <> "P" THEN Main
char = RX_BYTE
IF char <> "S" THEN Main
char = RX_BYTE
IF char <> "X" THEN Main
Instead of going back to main you could bail out if you id a 6 byte command and keep going for 8.
mydata VAR Byte
main:
SERIN 16,16468,[noparse][[/noparse]HEX mydata]
SELECT mydata
CASE 2
·· 'CODE FOR THE "ON" COMMAND
CASE 3
·· 'CODE FOR THE "OFF" COMMAND
CASE 9
·· 'CODE FOR THE "RGB" COMMAND
CASE 14
·· 'CODE FOR THE VIDEO COMMAND
ENDSELECT
GOTO main
I have to say I couldn't configure 38400 baud but·I captured the last byte everytime at 9600 on a BasicStamp OEM2
Jeff T.
It appears that the first 2 byte give you the an indication of the number of bytes to follow and 2 bytes of 00 that·you can ignore.
Read the first 2 byte and with a little trial and error, an if statement and a pause statement you might be able to time the input and restart at·the 5th byte ··After all that's what bit-serialis all about.
POWER ON: 02 00 00 00 00 02
POWER OFF: 02 01 00 00 00 03
Input 1 RGB 1: 02 03 00 00 02 01 01 09
Input 2 RGB 2: 02 03 00 00 02 01 02 0A
Input 3 RGB 3: 02 03 00 00 02 01 03 0B
Input 4 COMPONENT: 02 03 00 00 02 01 12 1A
Input 5 VIDEO 1: 02 03 00 00 02 01 06 0E
Input 6 VIDEO 2: 02 03 00 00 02 01 07 0F
Input 7 S-VIDEO 1: 02 03 00 00 02 01 0B 13
Input 8 S-VIDEO 2: 02 03 00 00 02 01 0C 14
Input 9 RGB DIGITAL: 02 03 00 00 02 01 1A 22
Input 0 SDI: 02 03 00 00 02 01 1B 23
PICTURE MUTE ON: 02 10 00 00 00 12
PICTURE MUTE OFF: 02 11 00 00 00 13
DISPLAY MUTE ON: 02 14 00 00 00 16
DISPLAY MUTE OFF: 02 15 00 00 00 17
LENS SHUTTER ON: 02 16 00 00 00 18
LENS SHUTTER OFF: 02 17 00 00 00 19
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Have Fun
TR
What I did was Serin the first two bytes then put the next four bytes into another array. As long as I get the last byte I can determine what button was pushed. The second byte would always tell me what direction to go whether it was an On/Off or input. With a few If/Then's it worked great. The code ran all weekend with no trouble.
You all were a great help, thanks again,
Steve