BS2 Master - Slave

Tumbler · 2009-10-19 06:46

Hello,

I'm planning to make a bs2pe used as an eeprom controller.
see picture...

About the eeprom controller:
i want to make a FAT-based eeprom controller: sending data, receiving data, get directorys etc...
The internal eeprom of the slave would be used for storing package information (date, time, id, package length, wich eeprom is used, address data,...)

I have read an article from Jon Williams ( a tale of two stamps), but as i can see the master can only talk to the slave? or is it possible in two ways?

And this slave code: SERIN SIOpin\FCpin, N2400, 200, LCD_Update, [noparse][[/noparse]ioByte]
does it mean that the slave only can receive data if the FCpin is high? that's not clear for me.
and can i use the same code·for the master? so i can talk in two ways?

regards

dev/null · 2009-10-19 09:56

Yes you can talk both ways. That's why you are using flow control. This will prevent one sender from sending data until the receiver is ready. SERIN and SEROUT will control the flow pin, you don't have to do anything with it.

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Don't worry. Be happy

Tumbler · 2009-10-19 12:32

Ok Dev/null

After some tests, this is what i have:

Master (a basic stamp2)

SIOpin CON 14 ' serial I/O
FCpin CON 15 ' serial flow control
CMD     CON 250 'cmd signal
ACK     CON 254 'ack signal
ERR     CON 255 'error signal
DIR     CON 0   'dir command
GDATA   CON 1   'get command
PDATA   CON 2   'put command
i VAR Byte
j VAR Byte
 
Main:
  SEROUT SIOpin\FCpin, Baud, [noparse][[/noparse]CMD,PDATA]  ' send put command to slave
  DEBUG "put command send...",CR

  ' now wait for ACK signal
  SERIN SIOpin\FCpin, Baud,[noparse][[/noparse]WAIT(ACK),j]
  DEBUG "ack + answer reveived... Answer:",DEC j,CR

END

 
Ready:
  DEBUG "ack received ",CR
  GOTO Main
 
TimeOut: '--> [b]not used this time
[/b]   DEBUG "no ack received ",CR

SLAVE ( a BS2pe)

CMD     CON 250 'cmd signal
ACK     CON 254 'ack signal
ERR     CON 255 'error signal
DIR     CON 0   'dir command
GDATA   CON 1   'get command
PDATA   CON 2   'put command
' -----[noparse][[/noparse] Variables ]-------------------------------------------------------
i VAR Byte

Main:
DO
  'wait for CMD command, with command type(i)
  SERIN SIOpin\FCpin,Baud,500,Check,[noparse][[/noparse]WAIT (CMD), i]
  DEBUG "Reveived from master: ",DEC i ,CR
  BRANCH i, [noparse][[/noparse]Directory, GetData, PutData]
  'We received an illegal command
  DEBUG "Error command...",CR
  DEBUG "Send Ack + error back",CR
  SEROUT SIOpin\FCpin,Baud,[noparse][[/noparse]ACK,ERR]
LOOP
 
Check:
  'do something check here
  GOTO main
 
Directory:
  'we received a DIR command
  PAUSE 1000    'slave is busy stamp
  SEROUT SIOpin\FCpin,Baud,[noparse][[/noparse]ACK,240]
  GOTO Main
 
GetData:
  'we received a GET command
  SEROUT SIOpin\FCpin,Baud,[noparse][[/noparse]ACK,222]
  GOTO Main
 
PutData:
  'we received a PUT command
  PAUSE 3000  'slave is a very busy stamp
  SEROUT SIOpin\FCpin,Baud,[noparse][[/noparse]ACK,200]
  GOTO Main

With these examples i can send a DIR,GET and PUT command to the slave. (slave answers with a ACK and a dec value)
But how can i prevent to send a command while the slave is busy?
i think i have to check the FCpin, but i don't know how to do it.

Tracy Allen · 2009-10-19 15:37

Tumber,

Is it not working?

The SERIN commands in the slave and the master control the output state of the FCpin. When the slave hits a SEROUT, it checks its FCpin "clear to send" as an input to see that the master is ready. And vice versa, when the master hits a SEROUT, it checks its FCpin "clear to send" as an input to see that the slave is ready to receive. So the flow control goes both ways.

Be sure you have ~1kOhm resistors in the lines between the two stamps, just in case there is a contention. That shouldn't happen in this program but it is a precaution.

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Tracy Allen
www.emesystems.com

Tumbler · 2009-10-19 15:57

Tracey,

The code above is working, but when the master sends 2 commands i don't receive the ACK anymore. In fact, i don't receive anything from the slave.
example (2 commands)
SEROUT SIOpin\FCpin, Baud, [noparse][[/noparse]CMD,PDATA]· ' send put command to slave
pause 10
SEROUT SIOpin\FCpin, Baud, [noparse][[/noparse]CMD,GDATA]· ' send get command to slave

Do i have to check the FCpin before i send a command?
I tried if the pin is low or high, but it takes me to nothing.

·

Tumbler · 2009-10-19 16:02

Ahhhhh, i forgot to check the ACK signal.

This is working now...

    'send first command
    SEROUT SIOpin\FCpin, Baud, 1000,TimeOut,[noparse][[/noparse]CMD,0]  ' send put command to slave
    SERIN SIOpin\FCpin, Baud,[noparse][[/noparse]WAIT(ACK),j]
    DEBUG "ack + answer reveived... Answer:",DEC j,CR
    
    PAUSE 1000 'let's take a break
    
    'send second command
    SEROUT SIOpin\FCpin, Baud, 1000,TimeOut,[noparse][[/noparse]CMD,1]  ' send put command to slave
    SERIN SIOpin\FCpin, Baud,[noparse][[/noparse]WAIT(ACK),j]
    DEBUG "ack + answer reveived... Answer:",DEC j,CR

yihaa, it's working...

BS2 Master - Slave

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