Serout WORD variable ???

fiveslo

How can I program my SX28 to output a WORD variable serially?· I believe·I have the SERIN side working, since, when from a terminal program, I send a "channel" to sample, I have successfully made the SX display the channel I've sent, since the channel value is 0-11, "byte territory" all works or at least appears to work correctly.· as you can see... I'm still working on my TLC2543 project, and would like to output serially the WORD variable "result", to a BS2p.· I've tried and mostly hacked all examples that I've found on the web but to no avail....· Is there a way to SEROUT what you see in the WATCH directive???· Below is a copy of code I've tried in the TX_BYTE subroutine....

' ------------------------------------------------------------------------- 
' Device Settings 
' ------------------------------------------------------------------------- 
DEVICE SX28, OSCXT2, TURBO, STACKX, OPTIONX 
FREQ 4_000_000 
' ------------------------------------------------------------------------- 
' IO Pins 
' ------------------------------------------------------------------------- 
sclk VAR RC.7 ' clock out from SX/28 to AD2543 
sdo VAR RC.6 ' data out from SX/28 to AD2543 sdi 
sdi VAR RC.5 ' data in from AD2543 sdo to SX/28 
ADcs VAR RC.4 ' AD2543 chip select, active low 
Sin VAR RA.1 ' pull-up via 4.7k 
Sout VAR RA.0 
' ------------------------------------------------------------------------- 
' Constants 
' ------------------------------------------------------------------------- 
Baud CON "T9600" ' open for single wire 
' ------------------------------------------------------------------------- 
' Variables 
' ------------------------------------------------------------------------- 
serbyte VAR Byte ' serial IO byte 
ADch VAR Word ' selects AD external channel 0-10 
result VAR Word 
temp1 VAR Byte 
temp2 VAR Byte 
temp3 VAR Byte 
tmpW1 VAR Word 
' ------------------------------------------------------------------------- 
' Watch Directives 
' ------------------------------------------------------------------------- 
WATCH result,13,UDEC ' display 12-bit result variable, value in millivolts 
' ========================================================================= 
PROGRAM Start 
' ========================================================================= 
' ------------------------------------------------------------------------- 
' Subroutine Declarations 
' ------------------------------------------------------------------------- 
TX_BYTE SUB 1,2 ' transmit byte to BS2p serial interface 
RX_BYTE SUB ' receive byte from BS2p serial interface 
' ------------------------------------------------------------------------- 
' Program Code 
' ------------------------------------------------------------------------- 
Start: 
HIGH ADcs ' make CS output 
LOW sclk ' make clock 0-1-0 
LOW ADcs ' select TLC2543 
ADch=$b ' make dummy conversion to intialize converter 
GOSUB ADread 

Get_Channel_Voltage: ' get data from specified ADC channel 
serbyte=RX_BYTE 
ADch=serbyte 
GOSUB ADread ' get millivolt data from channel specified 
BREAK() ' update result variable in watch window 
TX_BYTE result 
GOTO Get_Channel_Voltage 

END 
' ------------------------------------------------------------------------- 
' Subroutine Code 
' ------------------------------------------------------------------------- 
ADread: 
LOW ADcs 
ADch=ADch<<8 
SHIFTOUT sdo,sclk,MSBFIRST,ADch\12 ' mode, left justify ADch 
SHIFTIN sdi,sclk,MSBPRE,result_MSB\4 ' get result, 12 bits 
SHIFTIN sdi,sclk,MSBPRE,result_LSB 
HIGH ADcs ' deselect chip 
tmpW1=result**14464 ' convert count to millivolts 
result=result+tmpW1 
RETURN 

RX_BYTE: 
SERIN Sin,Baud,temp1 ' receive a byte 
RETURN temp1 ' return to caller 

TX_BYTE: 
temp1=__PARAM1 ' save byte 
IF __PARAMCNT=1 THEN ' if no count 
temp2=1 ' set to 1 
ELSE 
temp2=__PARAM2 ' get count 
IF temp2=0 THEN ' do not allow 0 
temp2=1 
ENDIF 
ENDIF 
DO WHILE temp2>0 ' loop through count 
SEROUT Sout,Baud,temp1 ' send the byte 
DEC temp2 ' decrement count 
LOOP 
RETURN

I even tried to output words within "quotation marks" as was shown in the RFID SX/B example, and the literals within quotes displayed correctly, yet when I replaced the literal within quotes with my variable... 'result'... without quotes... the display from the terminal program didn't give me what I saw in the debug window of SX/B...

TX_BYTE: 
 Use: LCD_OUT [noparse][[/noparse] aByte | string | label ] 
' -- "aByte" is single-byte constant or variable 
' -- "string" is an embedded literal string 
' -- "label" is DATA statement label for stored z-String 
temp1 = __PARAM1 ' byte or string offset 
IF __PARAMCNT = 2 THEN ' string specified? 
temp2 = __PARAM2 ' yes, save base 
DO 
READ temp2 + temp1, temp3 ' read a character 
IF temp3 = 0 THEN EXIT ' if 0, string complete 
SEROUT Sout, Baud, temp3 ' send the byte 
INC temp1 ' point to next character 
temp2 = temp2 + Z ' update base on overflow 
LOOP 
ELSE 
SEROUT Sout, Baud, temp1 ' send the byte 
ENDIF 
RETURN

I plan on·"replacing" the terminal with the BS2p,·but since I can't get·this to work with the terminal I'm stuck·and really need some help...Rob

Chris Savage

A word variable must be sent as two bytes. This is not a limitation of SX/B but the way the serial protocol is defined.· Depending on the nature of the system you could send it lowbyte/highbyte or highbyte/lowbyte. Take care.

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Chris Savage
Parallax Tech Support

Sparks-R-Fun

Rob,

As Chris pointed out, you will need to call TX_Byte twice since a byte is expected for serial transmission and you want to transmit the double-byte value that is held in a word variable.

Something like the following should work:

TX_BYTE Result__MSB
TX_BYTE Result__LSB

The "__MSB" and "__LSB" suffixes are automatic aliases SX/B creates for word variables so that the individual bytes that comprise the variable can be addressed separately. Pretty cool, eh?

As Chris also noted, you may need to switch the order of the statements if your BS2 is expecting the Least Significant Byte to be sent first.

Also, depending upon the capabilities of the terminal program you are using, you may not be able to visually recognize the correct values. Your terminal program will likely attempt to display each byte as a character or interpret it as a control code of some kind.

- Sparks