Communications Example : PC to PIC bi-directional dialogue

1 Attachment(s)

Judging by the emails I'm getting, folks have missed this hidden away at the end of another thread... so it's been repeated with a thread all of it's own.

Here's a sample program, thrown together for fun this lunchtime, to demonstrate bi-directional dialogue with a PC running something like Hyperterminal. It runs at 300 baud so almost any PIC will run it without an Xtal or Resonator (but best with!!!!).

The object of the program is to demostrate how commands can be passed from the PC User and acted upon by the PIC.

Yes, whatever you type on your PC is echoed back to you as feedback. The program is reasonably interactive... it tells you when you're Bad!, and tells you when you're OK. UPPERCASE and lowercase and cOmBINatIOns are handled with reasonably idiot-proof command interpretation... this is done by parsing the received command line (in a simplified manner for this example) rather than the usual way of having SERIN (or whatever) WAITing for a valid command.

You can even use the BACKSPACE Key and have the PIC perform rudimentary line editing.

PIC has five LED's which can be remote controlled in a variety of ways with commands like ON, OFF, BLINK, SWEEP and BEER. The major commands have sub-parameters which can be added to make control more interesting. Plenty of expansion for you to do your own thing.

Example:

ON Switch ON all LEDs
ON 2 Switch ON LED number 2

you can even have abnormally large gaps between the Command (eg ON) and the sub-parameters (eg 2)

ON 4 7 Switch ON LED number 4 for 7 seconds
BLINK 1 15 Blink LED number 1 15 times
OFF 1 Switch OFF LED number 1
SWEEP 25 Sequentially Sweep all LEDs 25 times

Try to break it (if you can) by typing combinations of garbage or having line lengths bigger than 10 bytes (my preset communications buffer maximum)....

Full instructions in the program comments.

Melanie

1 Attachment(s)

Some of you may not have PBP, but might like to try the program to play with... so I've appended the HEX ready to burn into a 16F628.

LED1 is on RA0, kathode to PIC, anode to Vdd via Resistor (eg 330R). LED2 is on RA1 similarly. LED3 is on RA2. LED4 is on RA3 and finally LED5 is on RA4.

Connect RB1 (RX) via 1K5 Resistor to PC pin 3 on 9-Pin D Connector. Connect (TX) RB2 via 1K5 Resistor to PC pin 2 on 9-Pin D Connector. Connect your PICs Vss (0v) to PC pin 5 on 9-pin D Connector.

You don't need an xtal or Resonator, and you don't need to worry about connecting the MCLR pin either. Those pins should be left unconnected. Just the LED's and the connections to your PC.

The appended file is a HEX file. Unfortunately this forum does not allow the uploading of files with HEX extensions, therefore rename comms1.txt as comms1.HEX before programming.

Melanie

Hi Melanie,

I assume that this will only work with a program compiled with PicBasic Pro and not PicBasic?

I have just purchased PicBasic and I planned to use this program for testing my programmer ( Velleman P8048), but I see that you use the DEBUG/DEBUGIN commands for communicating with the PC.

My Compiler manual says that DEBUG is not supported although it is syntax checked!

Can I not use the SERIN and SEROUT commands instead?

I haven't worked out how to address PortA pins yet/ Seems that all I/O points to PortB?

Regards

PaulB

You should be able to reassign the I/O to whatever pins you fancy. I put the LEDs on PortA from memory, so it was obvious to put the other stuff on PortB.

Sure, you can use SERIN/OUT.

I do check examples like this before posting them... It should port to PBC... however, not having it I'm reluctant to post examples and code that I haven't tried and tested. somebody will always come back and say this or that didn't work and I'd have no way of checking it.

Hi Melanie,

Thanks for the reply.

I thought that the SERIN and SEROUT were OK, but wanted to check.

Off topic, I'm really looking for a started guide to the use of PBC. The manual with it gives the syntax of the language tokens etc, but is not clear on use of directives etc and how to change the type of PIUC.

I thought that I should have simply been able to run your demo throug the compiler and get a HEX file at the end, but it barfs at the first @ directive!

I'll have a look through the forum again and post a note if I dont find anything.

Regards

Paulb

1 Attachment(s)

Hi Melanie...

I am having a little problem with your program.

I loaded it into the 16f628a, and it appears the characters are getting to the rx port, but no echo's or messages....

Hi...

Sorry it's taken me so long to verify this... just so much work and so little time.

Worked straight away witha 16F628A out of the box... but... then I tried it on a normal 16F628 (just a random selection from stock)... and I had comms errors!... not all the keys on the keyboard would echo, and those that did were wrong.

So I recompiled for a 4MHz xtal (Resonator actually using XT_OSC), added the bits... and tried the chip that was giving me problems... whoo-hoo... away it ran without errors.

This just proves that Async comms even at 300 Baud are not always reliable on internal oscillator. The variances between individual chips are just too great.

I shall post this on the forum.

Melanie

Hello,

I have a problem with this sample. When a open PICBASIC Terminal and type ON nothing happens but when a type ON 1 the PIC return Bad!.

Whats seems the problem, i think the PIC works fine because in the terminal i get the Bad! answer from the PIC

Thanks,
David

Please see the previous posts on this thread. You either have the wrong baudrate, or your PICs internal oscillator is out of spec and you need to recompile using an xtal or resonator.

I use the baudrate provided in the source code "300 baud, 8 Data Bits, No Parity, 1 stop Bit, No Flow Control".
The problem is i get errors while compiling your code, i use version 2.1.3 of Proton+.

Code:

Error at Line [112] In file [COLOK.BAS] *** Value Expected! *** Error at Line [165] In file [COLOK.BAS] *** Variable or Value is Missing! *** Error at Line [170] In file [COLOK.BAS] *** Square opening bracket '[' missing! *** Error at Line [183] In file [COLOK.BAS] *** Square opening bracket '[' missing! *** Error at Line [211] In file [COLOK.BAS] *** Syntax error! *** Error at Line [247] In file [COLOK.BAS] *** Syntax error! *** Error at Line [250] In file [COLOK.BAS] *** Misplaced or Incorrect 'ENDIF'. Also check its corresponding IF Command! ***

Regards,
David

Weird error message if you'd copy/paste the Melanie's code...Be sure you use MELABS compiler.

My examples are NOT written for Proton but for MeLabs PBP and are posted on this forum and on MeLabs website. The code works perfectly when used with compiler it was intended for.

Some clarifications if you please

Hello Melanie

I have seen the code you posted. I have a couple of queries and would like to know your opinion on them.

You use a step wise approach of building the command in the buffer by reading characters one by one. Can I use a construct like this and get away with it? If not, what could be the catch?

Code:

' wait for a command terminated by CR hserin [STR CmdBuf\16\13]

You compare commands with templates in EEPROM. Is there a way to avoid this and compare directly with templates in program space? I plan to have a strcmp function for each template I want checked. So, I might invoke it like this

gosub CheckCmd1
if Result then Command1
gosub CheckCmd2
if Result then Command2

Each CheckCmd function will check the Command Buffer against the template it has.

I am trying to do this
Command1 - TS ddmmyy hhnn <CR> Time Set
Command2 - GL <CR> Get Log
Command3 - CL <CR> Clear Log

I'd like to know what you think of this approach

Thanks
Jerson

Yes you can read in a string of characters the way you specify... but the problem is you are locked in the HSERIN or SERIN command until the number of characters that you specify in your string have arrived. If it's a keyboard input from a host for example, and they go off for a Coffee and a natter in the little-boys room half-way thru the string, then so does your PIC. The best way is to poll the Received Flag in the USART by background interrupt and continually feed a ring buffer. But that's a subject for another time.

No problem with comparing against what's in program-codespace rather than in EEPROM. My example was written that way so people can understand and play with it more easily.

Thank You

Melanie

Thanks very much. Your feedback has been helpful. Input will be through another PIC and so the human speed does not matter.

Jerson

1 Attachment(s)

Hi, I compile and get some errors. Sorry, but I had to attach it in a picture format.

Thanks.

Works for me...

H:\Data-Reference\PIC\PBP246>pbp -p16f628 comms1 -v
PicBasic Pro Compiler 2.46, (c) 1998, 2005 microEngineering Labs, Inc.
All Rights Reserved.
Pass 1:
Pass 2:
Code Gen:
Macro Pass:
PM.EXE H:\DATA-R~1\PIC\PBP246\comms1.ASM
PM Assembler 4.07, Copyright (c) 1995, 2004 microEngineering Labs, Inc.
921 words used.

You didn't explain how you've compiled it, but if you follow the example in the PBP manual you will have no problems.

If you're not using a MELABS compiler you'll have this error message, this error messge also apply on the low cost PBC compiler. It may also happen on PBP using MPASM as assembler.

i suspect the MPASM as assembler, just rem the config fuses (somewhere at the top of the code, and use the correct syntax for MPASM. See FAQ to know how to.

PIC 2 PIC comm

Hi
i m need of code for transmitting data from one PIC and another PIc receives the transmitted data,the communication is via SPI.i tried a lot bt i didnt get the o/p.i want to know what are the registers i have to configure.and i wantto know whether i have to dowload the transmitter prgm in one PIC and receiver program in another program.plz help me,i need it urgently.plzzzzzzzzzzzzzz.i m using pic16f877a

I converted this to run on a 16f676 it compiled but when I ran it I only get every other character back If I type Richard I get Rcad, if I type 123456789 I get 13579 and I guess because it's only "seeing" every other character I can not operate the LED
any ideals
thanks

Code:

' code by Melanie converted to be used with 16f676 by grounded ' added 4mhz external clock for this project to correct problems ' using microCode Studio and it's serial communicator ' ------------------------------------------------------------- ' ' CPU Hardware Layout ' ------------------- ' pin changed to use with 16f676 ' PortA.0 - RX cable via 1K5 Resistor to PC pin 3 on 9-Pin D Connector ' PortA.1 - TX cable via 1K5 Resistor to PC pin 2 on 9-Pin D Connector ' ' PortC.0 - LED1 to VDD via Resistor ' PortC.1 - LED2 to VDD via Resistor ' PortC.2 - LED3 to VDD via Resistor ' PortC.3 - LED4 to VDD via Resistor ' PortC.4 - LED5 to VDD via Resistor ' Don't forget to connect Vss to PC pin 5 on 9-pin D Connector pic16f676 ' FUSES SET IN INC FILE ' _XL_OSC, WDT_ON, MCLR_OFF, ' CPD_OFF, BOD_OFF, PWRT_ON,PROTECT_OFF DEFINE OSC 4 'EXTERNAL CLOCK SPEED 4MH.added for this project pause 2000 'DELAY TO LET STABILIZE AFTER POWER UP CMCON = 7 'COMPARATOR OFF VRCON = 0 'VOLTAGE REF. DISABLE ANSEL = 0 'DIGITAL OPTION_REG=0 'DEFAULT WPUA = 0 'NO WEAK PULLUPS INTCON=0 'INTERUPPTS OFF ' Debug (Communication) Defines (Transmit) ' ---------------------------------------- DEFINE DEBUG_REG PORTA 'CHANGED FROM B FOR 16F676 DEFINE DEBUG_BIT 1 DEFINE DEBUG_BAUD 300 DEFINE DEBUG_MODE 1 ' ' DEBUG (Communication) Defines (Receive) ' ---------------------------------------- DEFINE DEBUGIN_REG PORTA 'CHANGED FROM B DEFINE DEBUGIN_BIT 0 DEFINE DEBUGIN_BAUD 300 DEFINE DEBUGIN_MODE 1 ' Data @0,2,"ON",0,0,0,0,0 Data 3,"OFF",0,0,0,0 Data 5,"BLINK",0,0 Data 5,"SWEEP",0,0 Data 4,"BEER",0,0,0 Data 0,0,0,0,0,0,0,0 Data 0,0,0,0,0,0,0,0 Data 0,0,0,0,0,0,0,0 Data 0,0,0,0,0,0,0,0 Data 0,0,0,0,0,0,0,0 ' ' RAM Assignments and Variables ' ----------------------------- BadFlag var BIT ' Flag for Bad Command CounterA var BYTE ' Just a Counter CounterB var BYTE ' Just a Counter CounterC var BYTE ' Just a Counter CounterW var WORD ' Word-sized Counter Command var BYTE ' Holds the Command action to execute CommsBuffer var BYTE [10] ' Max Comms Command Line size CommsPointer var BYTE ' Pointer to data in Comms Buffer LEDStatus var BYTE DataA var BYTE ' Usage as Data Byte Xvariable var BYTE ' 1st Numeric Variable Yvariable var BYTE ' 2nd Numeric Variable ' ' Program Constants ' ----------------- BufMax con 10 ' Max size of data Buffer CommandMax con 10 ' Max number of COMMANDS to be processed ' ' Start - Initialise Processor ' ============================ TRISA=%00000001 TRISC=%00000000 'changed from B to C for 16f676 Xvariable=0:Gosub LEDsOFF ' All LEDs OFF ' ' Clear Buffer ready for start of New Command Line ' ------------------------------------------------ RestartLine: For CounterA=1 to BufMax CommsBuffer[CounterA-1]=0 Next CounterA CommsPointer=0 ' Set Pointer to Start of Buffer ' ' Communications (Closed) Loop ' ---------------------------- ReadLoop: DEBUGIN [DataA] If DataA<32 then If DataA=8 then ' Process BACKSPACE Key If CommsPointer>0 then ' --------------------- CommsPointer=CommsPointer-1 ' Rewind one position CommsBuffer(CommsPointer)=0 ' Erase character in Buffer DEBUG $08,$20,$08 ' Echo Erase sequence to PC Goto ReadLoop endif endif If DataA=13 then goto ENTERKey Goto ReadLoop endif If DataA>126 then goto ReadLoop DEBUG DataA ' Only Echo Printable Characters If DataA>96 then ' Convert all alphabetics to UPPERCASE If DataA<123 then DataA=DataA-32 endif CommsBuffer(CommsPointer)=DataA ' Save to Buffer CommsPointer=CommsPointer+1 ' Bump Pointer If CommsPointer<10 then goto ReadLoop ' Loop for next character ' ' Process [ENTER] Key ' ------------------- ' also execute if Command Buffer exceeded ENTERKey: ' ' This section Parses the Command Line ' ==================================== ' ' Look for Command WORD ' (scan through available Command vocabulary) ' ------------------------------------------- Gosub LSpace ' Remove Leading Blanks Gosub REnd ' Locate Command Word End If CounterA=0 then goto EchoCRLF ' Nothing to Process For Command=1 to CommandMax BadFlag=0 CounterB=(Command-1)*8 Read CounterB,DataA ' Get Preset Command word Length If DataA=CounterA then ' If Length correct, process entire word For CounterC=1 to CounterA CounterB=CounterB+1 Read CounterB,DataA If CommsBuffer(CounterC-1)<>DataA then BadFlag=1 Next CounterC If BadFlag=0 then goto GoodCommand endif Next Command ' ' Bad Command Word ' ---------------- BadMove: DEBUG REP $00\8,13,10,"Bad!" ' Tell User No Cigar EchoCRLF: DEBUG 13,10 ' New Line Goto RestartLine ' Loop Round and Do again ' ' Parse for First Numeric Variable (if any) ' ----------------------------------------- GoodCommand: Gosub ShuffleData ' Advance Command Line to start of next Word (if any) Gosub REnd ' Locate End of next word Gosub GetNumericWord ' Get numeric value If BadFlag=1 then goto BadMove ' Invalid Data Xvariable=DataA ' Save 1st Numeric Variable ' ' Now check for 2nd Numeric Variable (if any) on the Command Line ' --------------------------------------------------------------- Gosub ShuffleData ' Advance Command Line to start of next (last) Word (if any) Gosub REnd ' Locate End of word Gosub GetNumericWord If BadFlag=1 then goto BadMove ' Invalid Data Yvariable=DataA ' Save 2nd Numeric Variable ' ' Execute Command ' --------------- If (Command<4 and Xvariable>5) then DEBUG REP $00\8,13,10,"No such LED!" goto EchoCRLF endif If Command<3 then If Yvariable>9 then goto BadMove If Yvariable>1 then gosub WaitMessage endif If Command=3 then If Yvariable>60 then goto BadMove If Yvariable>5 then gosub WaitMessage endif If Command=4 then If Xvariable>5 then gosub WaitMessage endif ' ' ON LED Command ' -------------- If Command=1 then Gosub LEDsON If Yvariable>0 then CounterW=Yvariable*1000 Pause CounterW Gosub LEDsOFF endif endif ' ' OFF LED Command ' --------------- If Command=2 then Gosub LEDsOFF If Yvariable>0 then CounterW=Yvariable*1000 Pause CounterW Gosub LEDsON endif endif ' ' BLINK LED Command ' ----------------- If Command=3 then For CounterA=1 to Yvariable Gosub LEDsON Pause 200 Gosub LEDsOFF Pause 200 Next CounterA endif ' ' SWEEP Command ' ------------- If Command=4 then CounterB=Xvariable If CounterB<1 then CounterB=1 For CounterA=1 to CounterB For Xvariable=1 to 5 Gosub LEDsON Pause 100 Gosub LEDsOFF Next XVariable Next CounterA endif ' ' BEER Command ' ------------ If Command=5 then DEBUG REP $00\8,13,10,"Yes Please!" ' ' Tell User all executed OK ' ------------------------- DEBUG REP $00\8,13,10,"OK" Goto EchoCRLF ' ' Subroutine Area ' =============== ' ' Subroutine extracts Numeric Value from Command Line ' --------------------------------------------------- GetNumericWord: DataA=0 BadFlag=0 If CounterA>2 then Goto BadWord If CounterA>0 then CounterB=CommsBuffer(0) If CounterB<48 then goto BadWord DataA=CounterB-48 If DataA>9 then goto BadWord If CounterA=2 then CounterB=CommsBuffer(1) If CounterB<48 then goto BadWord CounterB=CounterB-48 If CounterB>9 then goto BadWord DataA=DataA*10+CounterB endif endif Return BadWord: BadFlag=1 Return ' ' Shuffle Data to remove processed word ' ------------------------------------- ShuffleData: For CounterB=0 to 9 CounterC=CounterA+CounterB If CounterC<=9 then CommsBuffer(CounterB)=CommsBuffer(CounterC) else CommsBuffer(CounterB)=0 endif Next CounterB ' ' Subroutine removes leading SPACES (Blanks) from Buffer ' ------------------------------------------------------ LSpace: If CommsBuffer(0)=32 then For CounterA=1 to 9 CommsBuffer(CounterA-1)=CommsBuffer(CounterA) Next CounterA CommsBuffer(9)=0 Goto LSpace endif Return ' ' Subroutine Locates end of Dataword in Comms Buffer ' -------------------------------------------------- ' CounterA on exit End Point REnd: For CounterA=0 to 9 If CommsBuffer(CounterA)=32 then goto REndExit If CommsBuffer(CounterA)=0 then goto REndExit Next CounterA CounterA=10 REndExit: Return ' ' Subroutine tells User to Wait ' ----------------------------- WaitMessage: DEBUG REP $00\8,13,10,"Wait..." Return ' ' Subroutine DISABLES LEDs ' ------------------------ LEDsOFF: If Xvariable=0 then LEDStatus=$1F else LEDStatus.0(Xvariable-1)=1 endif PortC=LEDStatus '*****CHANGED TO C FROM A Return ' ' Subroutine ENABLES LEDs ' ----------------------- LEDsON: If Xvariable=0 then LEDStatus=$0 else LEDStatus.0(Xvariable-1)=0 endif PortC=LEDStatus '******* CHANGED TO C FROM A Return End

I would query first that perhaps you are not receiving 100% good Data...

Replace ReadLoop with this code...

Code:

ReadLoop: DEBUGIN [DataA] DEBUG DataA," ",HEX2 DataA,10,13 Goto ReadLoop

This will echo the HEX representation of what has been received... so if you type Richard you should get...

R 52
i 69
c 63
h 68
a 61
r 72
d 64

where the character is what you typed along with its HEX as confirmation of good data...

If every 2nd character is not what you expected, then time to find out why...

thanks
I will "play" some more
I thought I mite have missed something when I converted

up date
I tried using hyperterminal and everything works just as it should
I then tried MCS serial communicator (again) with readloop get hex and all I got was R 52
SOO the code is good , the hardware is good there is just something I'm missing using MCS comm. One big difference hyperterm. is real time key stroke to echo, MSC only after manual CR.
I also tried realterm. sometime the echo worked but never the LED (BLINK, SWEEP, ON OFF ETC.) ideals.
thanks

Need your help

Dear Melanie

Please I need your help if , i try to construct project to control 8 devices by using pic16f84

one as transmitter and another pic as a receiver to control 8 relays and to read the status of relays which one is open and which one is closed , if the relay switch is on the led indicate that is on in transmitter (frist pic) in this case i can switched off.

would you please can you help me ?

thank you very much

Eng. ibrahim elalfy

my private E-mail is

[email protected]

Need your help

Dear Melanie

Please I need your help if , i try to construct project to control 8 devices by using pic16f84

one as transmitter and another pic as a receiver to control 8 relays and to read the status of relays which one is open and which one is closed , if the relay switch is on the led indicate that is on in transmitter (frist pic) in this case i can switched off.

would you please can you help me ?

thank you very much

Eng. ibrahim elalfy

my private E-mail is

[email protected]

Quote:

Originally Posted by ibralfy

Please I need your help if , i try to construct project to control 8 devices by using pic16f84
one as transmitter and another pic as a receiver to control 8 relays and to read the status of relays which one is open and which one is closed , if the relay switch is on the led indicate that is on in transmitter (frist pic) in this case i can switched off.

Good plan posting your real email address!
See this thread:
http://www.picbasic.co.uk/forum/showthread.php?t=1742
You'll get help, just post your info...

Hello,

¿How can I change the baud rate to 2400?. ........ Solved

Thank you

Re: Communications Example : PC to PIC bi-directional dialogue

I know not strictly to do with PIC Basic, but if anyone is interested, I rewrote this into ProtonBasic (Crownhill) :eek: and it works just fine. I'll post the code here when I'm on my own PC.