same objects differents cogs

Laurent R · 2009-04-10 13:13

I'm using an ADC (max1270) I have an object who read the convert value and it works well.

I want to launch a second cog within an infinite loop and this cog 'll read the converted value every 2 seconds (to manage an alarm).

So the "main" cog 'll be able to receive commands and read the converted value when I ask him.

I wonder as both cogs need to control the max1270 , they need the same object. Is it good or I have to write a second max1270 control object?

When the second cog is enable and run max1270 control, both cogs convert's results = 0 but if only the first is active the conversion is ok...

If I call the alarm method on the first cog, the result of the convertion is good too but I can't send him new commands...

Thanks for ideas

Laurent

Post Edited (Laurent R) : 4/10/2009 1:24:10 PM GMT

MagIO2 · 2009-04-10 13:37

I guess your problem is that you start the object twice. There is no need to do so, because usually the driver of a device is started in a separate COG. Either it waits for commands (like the FullDuplexSerial) or the driver runs endlessly to do it's job (like the TV/VGA drivers). As your COG which reads the MAX is working and repeatingly reading the voltage value, there should be a variable where you can find that value.
All your second COG program needs to know is the adress of this variable. It should not start the ADC object again! Because of the internal rules for driving the I/Os of the propeller, it's unpredictable what happens when both COGs drive the same PINs.
Maybe the Object has to be enhanced a bit with a function that returns the adress of the variable.

Mike Green · 2009-04-10 13:38

This is too complicated a description. Please provide a copy of your source code as an attachment to your message.

In general, if you have two cogs and each cog needs to access some device (like a MAX1270), you probably need to
have each cog request exclusive use of the device just before using it, then release it when done. This is done with
the LOCKxxx statements. The chapters on these statements in the Propeller Manual have examples of this.

Greg LaPolla · 2009-04-10 13:43

You cannot put an object into a cog. You can create a method and put that method into a cog like this:

PRI main
  cog := cognew(@readadc, @stack)

PRI readadc

REPEAT
  adc read code here
  waitcnt(clkfreq * 2 + cnt)

Something like this is what you need to do. You could use a pointer to point to a variable in hub ram and update that from readadc and then you could just access that variable at anytime to get the value.

Greg

localroger · 2009-04-10 13:45

@Laurent -- you should only have one cog directly controlling the ADC. It should leave the conversion result in Hub RAM where other cogs can read it. If other cogs need to exert some control over the ADC, they should leave "requests" in a Hub RAM variable which the cog that is actually controlling the ADC can check as a part of its loop and perform requested operations.

Laurent R · 2009-04-10 14:04

Here is my code...

As the max 1270 is alone, I thought it was good using the chip select pin to know when the max1270 is already at work... And so I wait that he not busy but maybe it's not the good way ...

Thanks for the help

Laurent

StefanL38 · 2009-04-10 20:42

Hello Laurent,

I took a quick look into your code
pretty long loop with a lot of commands in it

you putted some comments in between. I want to make a suggestion:
What do you think about the idea to divide these 640 ! lines of code in several methods
and give each method a selfexplaining name ?

When I learned programming I was told to do it straight structured. Every method does ONE thing

Imagine phoning with TWO people at the same time. You would not understand anything if they are talking at the same time to you
for the 1270 it is the same.
Did you check if the busy-pin is signalising busy REALLY ALL the time until the request is done.
As two cogs run completely independant from each other only the shortest time of the busy-pin signalising NOT busy is enough to
make the second cog shout into the request if te´he first cog from time to time.

The suggestion of localroger is the way to go. ONE cog talking dircktly to the ADC. All other cogs que requests via this cog.

Do you have an idea how you can code the ADC-result to be stored in a global variable or how it can be given back over a method
from the ADC-object ?

If you are performing different commands towards the ADC. Would it still be fast enough to do ALL possible requests to the ADC ALL the time
and provide the results in variables ?

best regards

Stefan

Laurent R · 2009-04-14 08:17

I understand your suggestions but actually enable the alarm method fail...

If the alarm method is the only one running, and if I add "serial.dec(value)" to display the result of the convertion

It display a "0"

So I think there is a problem when I use the adc method in a second cog...

I'm confused

Laurent

EDIT :

I try to start alarm method in the same cog and it display the right value ...

But as soon as I start it in a new cog it display 0 ... Even if alarm is the only method running

Post Edited (Laurent R) : 4/14/2009 9:34:29 AM GMT

StefanL38 · 2009-04-14 10:42

Hello Laurent,

you have your main-object and this object defines some other objects.

OBJ
    
  ser :         "Extended_FDSerial"    'For debug and serial com
  'ser :        "SerialMirror"
  max1270:      "Max1270"           'ADC interface
  fmt:          "Format"
  Alarm:        "Alarm"

then you start the method Alarm in the object "Alarm"

in the variable "val" you read in the ADC. This variable "val" is ONLY accessesible within the object "Alarm"
in other words everywhere from INSIDE the file "alarm.spin" you can access the variable "val" directly

OUTSIDE from the file "alarm.spin" you can NOT access the variable "val"

you could write a method in the file "Alarm.spin"

by the way: you are using the same name for THREE different things filename, object and method have the name "alarm"

here MY "write maintainable code-ALARM" starts yelling at double-red !
take 10 minutes and think about what could be DIFFERENT and senseful names for the filename, object and the method

(maybe even some of your own confusion is caused by the same names)

OK back to the main thing:
you can write a method in the file "Alarm.spin" named "Get_value" wich returns the value of variable "val"

If this is not the problem give a detailed info of what is going wrong

I mean attach a program-version which "start alarm-method in the same cog"
and add a mark something like "<

here i get the right value" at the interesting line of code
and a programversion where it does not work

another thing you start Extended_FDSerial inTWO cogs with the same pins 31,30
every command ser.start(31, 30, 0, 9600) starts a NEW cog !

as cogs run independent from each other both can send at the same time and will mix up their signals

Maybe you could write something about what your whole program should do

It takes much more time if I re-engineer your code than you to write a description

best regards

Stefan

Laurent R · 2009-04-14 11:31

Hi Stefan

Here are 3 differents codes where you could see where the things gone wrong...

I put some comment to help you to understand my problem...

here is the goal of my code :

I want to run in a "main" cog a method who receive comands on a serial link, do a task and send back an answer.

One of thoses task is reading an ADC, the MAX1270.

But I also want to use the MAX1270 in a second method running in a second cog. This second method is a infinite loop who get result of conversion wait few seconds and get result again (for debugging I send value to serial terminal). The result is used to set an alarm or not.

While the alarm method is running, I should be able to get new commands on the serial link (reason for the second cog ...)

For the serial object, pin 31,30 are just used fro debug, the other object is running with RS_RO and RSDI (pin 3 and 6)

Thanks

Laurent

StefanL38 · 2009-04-14 20:27

Hello Laurent,

the cognew command should be done INSIDE the object

I have a quick guessing. You are setting the CS-pin high in the main-method
if you start another cog for RunAlarm the CS-IO-pin is switched in this OTHER cog

as long as ONE cog has an IO-PIN HIGH the PIN will STAY high even if all other cogs
switch it to low as the IO-Pin-state of all cogs are ORed with each other

to test this simply send back a harcoded value for millivolts

instead of

PUB RunAlarm(ValAlarmHi,High_Pos,ValAlarmLo,Low_Pos,Latch_Alarm)| signe '
  ser.start(31, 30, 0, 9600)
  'dira[noparse][[/noparse]OTOR1] ~~
  repeat
 
    val:=max1270.get_millivolts(0, false, false) ' canal 0  / range : -10 +10
    HIGH(CS) 
    ser.dec(val)
    waitcnt(clkfreq*10 +cnt)

code

PUB RunAlarm(ValAlarmHi,High_Pos,ValAlarmLo,Low_Pos,Latch_Alarm)| signe '
  ser.start(31, 30, 0, 9600)
  'dira[noparse][[/noparse]OTOR1] ~~
  repeat
  
    val:=max1270.get_millivolts(0, false, false) ' canal 0  / range : -10 +10
    HIGH(CS) 
    'ser.dec(val)
    ser.dec(123)
    waitcnt(clkfreq*10 +cnt)

and see if you get back 123 when alarm.startalarm is used

This bug is caused or maybe I should say "supported" by your way of coding

Your way of coding is to do MORE than one thing in ONE method and spreading functionality over several places
here a High(CS) and there a outa[noparse][[/noparse]CS]~ and already catched a bug !

I highly recommend to RE-code your program in a way that ONE method does ALL the details belonging to ONE thing

this means there is one object max1270 which does EVERYTHING for the max1270:
- initialisation of ALL pins related to the max1270
- bitbanging of ALL pins related to the max1270 HIGH(CS) included and NO other places that switch ANY IO-pin related to the max1270

then add a start-method "Start_Max1270" inside the object Max1270
this method starts a cog with another method that has an infinite running loop and reads in the value ALL the time
and stores it into a global variable "ActualVal" defined in the Max1270-object

then add a method "Get_Max1270_Value" inside the object Max1270 which simply is

PUB Get_Max1270_Value 
  result := ActualVal

then you can call the method Get_Max1270_Value
from everywhere you want to do that
with

  val := alarm.Get_Max1270_Value

and always get the actual value of the max1270

best regards

Stefan

Post Edited (StefanL38) : 4/14/2009 8:33:57 PM GMT

Laurent R · 2009-04-15 07:51

Thanks stefan, I'll try what you said ...

I already try to ser.dec(123) and it works ...

So I'll try to clean up all this mass and do something better and more simple ...

Hope it 'll be good

Laurent

Laurent R · 2009-04-15 09:05

Stefan you are a god to me [noparse]:)[/noparse]

I restart a blank project and made everything you said and tadaaam

I'm now able to read the value from the first cog and from the second...

Thanks again

I hope that 'll be good now [noparse]:)[/noparse]

Laurent

same objects differents cogs

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