Need Help reading form EEPROM

Ryan Rafferty

Let me start by saying that I am VERY new to Propeller and Spin. I am having a problem and I have searched the forums to no avail.

I have a spin application running on my Propeller that is launching 6 cogs to each do the same thing, only with different pins.

Here is a bit of my code that I will explain.

OBJ
  BS2 : "BS2_Functions"
  ser : "TRXEngineModified"

PUB Main
  cognew(StartScan(1),@cogSpace1)
  cognew(StartScan(2),@cogSpace2)
  cognew(StartScan(3),@cogSpace3)
  cognew(StartScan(4),@cogSpace4)
  cognew(StartScan(5),@cogSpace5)
  cognew(StartScan(6),@cogSpace6)
 
PUB StartScan(chan) | rbyte, txPin, rxPin, i, sAdd, eAdd
  txPin := (rxPin := (chan * 2) - 2) + 1                         'set the transmit and receive pins based on the channel we are monitoring
  repeat
    rbyte := ser.receiveCharacter(19200, rxPin)             'This section is working fine...FROM HERE...
    pause(200)
    if rbyte == 77
      ser.transmitString(string("M?:009A",13,10,13,10), 19200, txPin)
    elseif rbyte == 65
      ser.transmitString(string("WR:",13,10),19200, txPin)
    elseif rbyte == 76                                                   'This section is working fine...TO HERE
      eAdd := (sAdd := (chan - 1) * 150) + 130               'Set the beginning and ending address to read from the EEPROM
      repeat i from sAdd to eAdd
        ser.transmitCharacter(BS2.Read_HighMem(i, 1), 19200, txPin)   'This is the part I am having a problem with.  See EXPLANATION BELOW
      sAdd~
      eAdd~
      i~
      
    rbyte~

EXPLANATION
So, if I run this app, it works great. No problem at all as long as I only request data from 1 of the cogs. As soon as I request data from a second cog (Does not even have to be simultaneously) it does not read the EEPROM correctly. I reboot the Propeller and it works fine again, until I try to have another cog read from the EEPROM.

Can someone point me in the right direction. Keep in mind I have no experience with Spin. I have this project running flawlessly on 6 Basic Stamp 2e chips, but I want to consolidate to a single Propeller running 6 cogs.

BTW, if I omit reading from the EEPROM to get the next character, and instead use a predetermined character, the program runs without a hitch. However, I need to be able to pull this data from the EEPROM and send it out a pin via serial communicaitons.

Another possibility would be to read it once on bootup and store the data in a variable, but it is 129 bytes of data per channel and I don't know how to go about that.

Thanks in advance for any help you can give me.

Ryan

Gerry Keely

Hi

I'm not a spin expert but you appear to be trying to access the one eeprom from six cogs(??).

If so this·can be a problem··as all cogs would be trying to access the eeprom simultaneoulsy and also·input/output pins are OR'ed together. If one cog leaves a pin in a high state it cannot be set low by another( ie 1 or 0 =1).

Regards

Gerry

Mike Green

Gerry is right. You're trying to read from the EEPROM potentially simultaneously from 6 different cogs and there's only one EEPROM, only one I2C bus.

Your idea of reading the table from EEPROM into a variable (or set of variables) is a good idea. You could easily have a 6 x 129 byte array (774 bytes total) since the Propeller has more than enough memory for your project. You'd access the array using the channel number and index like "table[noparse][[/noparse] chan*129 + i ]" and you'd just declare the array as "VAR byte table[noparse][[/noparse] 6 * 129 ]".

Note that it's impossible to tell what you're trying to accomplish from your program fragment. If this data table is fixed, you could simply define it in a DAT section like:

DAT
table   byte   1, 2, 3, 4, 5, 6 ....
          byte   11, 12, 13, 14, 15, 16 ...

and so on for a total of 774 values.

Kye

Here Ya go. It also includes locking support for multi cog acess.

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Nyamekye,

Ryan Rafferty

Gerry and Mike, Thanks for your help with this. I understand the concern of simultaneous access to the EEPROM, but the host system that sends the requests for data will only send requests to one of the six cogs at a time. Then it will wait for the full response before requesting data from another cogs. So it wouldn't be accessing it simultaneously.

Gerry, I didn't know that if a pin is set high by one cog, it cannot be set low by another. That's good information for me moving forward. Thank you for that.

Mike, I like your idea of using the byte array. I am used to Visual Basic and was getting hung up on the table[noparse][[/noparse]1..6] but then realized that I can't hold an entire string in each element of the array. Since I can't have a two dimensional array (matrix) I thought that method wouldn't work. Your suggestion of table[noparse][[/noparse] chan*129 + i ] is a great idea. I will try that next and let you know how it works out. The data table is not fixed, but very rarely changes. If I could read it from the EEPROM on bootup and store it in the variables, that would be great.

Kye, I have just downloaded your code and it looks great. BTW, I really like the simplicity of the TRXEngine. Thank you for your contributions.

I really appreciate all the help.

Thanks,
Ryan

Ryan Rafferty

Gerry, You said that if a pin is left high by one cog, it cannot be brought low by another.

If a pin is left low when a cog is finished with it, can another cog then use it switching it low and high and then leaving it low again ?

I have a serial LCD Display that I can only send data to form one cog. If I try to output to it from another cog, it doesn't display anything. If I got back and trigger an output to it form the original cog, it displays fine. Could that be my problem there ?

Thanks,
Ryan

PS. Still working on the EEPROM read into memory. I will post once I resolve that and let you know what worked best.

Ryan Rafferty

OK, so I used Kye's function (I2C_ROMEngine.readPage) to load the data into the RAM from the EEPROM on bootup and that worked great. Rather than looping byte by byte through 774 elements of an array, I just reference the RAM using Kye's TRXEngine.transmitString function and pointing to the address where I loaded the data.

Now I just need to clean up the function that writes to the EEPROM for updates.

Thank you so much for all of your help.

Ryan

Gerry Keely

Hi ryan



If you look at page 26 of the Propeller Manual it explains how the I/O resources are shared by the cogs, better than I could explain it.

you can get a copy of the manual here

http://www.parallax.com/ProductInfo/Microcontrollers/PropellerGeneralInformation/PropellerMediaPage/tabid/832/Default.aspx



Gerry

Ryan Rafferty

Kye, is there a way to implement a timeout in your TRXEngine receiveCharacter function. Right now it waits indefinitely which works great for my application, I just have another idea that would be nice to have a timeout if no additional data comes in after X number of milliseconds.

Thanks for your help.
Ryan

Kye

First, attached is the new updated version of the TRX engine I'll release it soon.

Now, for timeout just do this.

PUB receiveCharacterTimeout(recieverPin, baudRate, timeoutInMilliseconds) | snapshot
 
  recieverPin := ((recieverPin <# 31) #> 0)
  snapshot := cnt 
 
  repeat until(timeoutInMilliseconds < (cnt - snapshot)) 
 
    ifnot(ina[noparse][[/noparse]recieverPin])
      reutn receiveCharacter(recieverPin, baudRate)
 
  return 0  

The code my be wrong but the idea is to just keep checking until the I/O line goes low as fast as possible until the time is up.



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Nyamekye,

Ryan Rafferty

That makes sense. I will give it a shot and let you know how it goes.

Thanks,
Ryan