Procedure with BS2 & shifters 74HC595 & 74HC165

Drago · 2009-07-15 17:44

Hello everybody,
·
No needs to say that I am new here!
Recently I discovered the BS and I am very sorry I didn’t have this opportunity 20 years ago.
It appears that we can use it in the application we already using different processor, but we do not have capabilities to change the software or preloaded process.
Now I will try to switch to BS, but I need little help in this:
Here is the application:
We have 43 “positions” and each position is connected to 2 inputs and 2 outputs (total 172 I/O).
I would like to use one BS2 with shifters 74HC595 and 74HC165.
Each “position is independent and applies the same process:
-········· Input #1 change the state (ON) = activate output #1 for time (10 seconds) next,
if input #2 change the state (from OFF to ON) it activates output #2 and deactivate output #1.
Output #2 stays ON until input #2 is ON even if the process repeats (input #1 trigger again,….).
When input #1 is triggered and input #2 is closed after time out (10 seconds) both outputs #1 & #2 should close.
·
As a beginner I wrote the code for the process, but I do not know how to implement this with the shifters for that many I/O’s?
' {$STAMP BS2}
' {$PBASIC 2.5}
·
DO
·
DEBUG ? IN5
DEBUG ? IN3
IN3 = 0
IF (IN3 = 1)· THEN
HIGH 14
·
PAUSE 10000
LOW 14
·
IF IN5 = 1 THEN
HIGH 15
ELSE
IF· (IN5 = 0) THEN
LOW 15
·PAUSE 3000
ENDIF
· ENDIF
·ENDIF
·
LOOP
·
Previously we used TPIC6B595, but I wasn’t able to make it happen. Today I order the 74HC595 and if anybody can help me with this code that will be great.
Thank you
Drago

stamptrol · 2009-07-15 18:03

Welcome aboard!

On the Parallax website you can download "What's a Microcontroller" which is a really good source for some of the common things we do with Stamps.

In particular, it has some articles on the use of the shift registers you mentioned.

I've done a couple of jobs with the expansion concept (only to 64 inputs, though) for a lumber tally system. Generally they work quite well as long as your process has enough processing time to cycle through the registers. Some experimentation may be required.

Cheers,

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Tom Sisk

http://www.siskconsult.com
·

Drago · 2009-07-15 19:22

Thank you Tom,
I get some samples from couple sources and the part I wrote work fine, but I wasn’t able to make happen with shifters.
It may happen that TPIC6B595 can’t work and I have to use 74HC595, so I am now on hold until I get them.
I am little bit older guy and it will take little bit until I swallow all info.
Drago

stamptrol · 2009-07-16 16:28

No worry, there are a lot of us "bit older" guys here.

I think your TPIC6B595 can be made to work but it does have a couple extra inputs compared to the 74HC595. Maybe comparing both data sheets you could cross match them.

Also, I may have steered you to the wrong resource.....have a look at the "Stampworks" document on the Parallax website.

Cheers,

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Tom Sisk

http://www.siskconsult.com
·

Drago · 2009-07-16 18:15

Thank you for your support Tom,
I downloaded Stamp works and it is great help.
As I mentioned I am new with programming, but I am a veteran in electronic hardware.
My experiment with TPIC6B595 it may work, because I implemented the code from Stamp works and I get one cycle of LED’s on (it doesn't repeat?), but I don’t know how to write my application to associate the particular inputs with outputs.
So I taught that will be better to eliminate problem with unknown hardware and use the 74HC595 which sample is written for.
The sample for 74HC165 also works fine each input change the state.
·
Regarding your comment from yesterday each process will be executed separately, so the “traffic” should not be a problem.
Scanning time it could be interrupted for ms until execute output, but this is not crucial.
Thank you

stamptrol · 2009-07-16 20:24

Keep at it!

Let me know if I can help further.

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Tom Sisk

http://www.siskconsult.com
·

dev/null · 2009-07-17 01:32

The 74HC595 and 74HC165 works very well with Stamps. Attached is a schematic for chaining 595's.

For your project you will need 11 input and 11 output shift registers, for a total of 176 I/O.

Attached is some code that might work for you.

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Don't worry. Be happy

Drago · 2009-07-17 16:57

Thank you dev/null,
I am waiting to get the 74HC595 and 74HC165 and I will try the configuration and will apply the code.

What about 74HC165? How they are connected?
Are they using the same communication line or they should be on different pins?
Some schematics I have require the resistor to distinguish inputs from outputs on same line.

I can have inputs on different three pins of BS2, and:
• Inputs 1 & 2 could be related only to outputs 1& 2 to execute my process,
• Inputs 3&4 related only to outputs 3&4,
• Inputs 5&6 related only to outputs 5&6, and so on.

That way will avoid the potential communication problem?

By the way how is in Norway?
Have a nice weekend
Drago

dev/null · 2009-07-17 19:02

I am not sure excactly how you would chain 165's, but they can use the same communication lines. I suppose you can connect them excactly as you connect the 595's.

In the code I wrote, which I post an update to here, I am assuming that you have inputs 1&2 related to outputs 1&2 of the same "position", and so on. If you didn't you'd get really confused!!

BTW Norway is beautiful this season. I live on the west coast, and do lots of windsurfing and robot-building!!

I had to correct an error in the code. The attachment manager in this forum is bugged, so I post the code here.

' {$STAMP BS2p}
' {$PBASIC 2.5}

iopin PIN 0
clockpin PIN 1
latchpin PIN 2

InBits VAR Byte(11)
OutBits VAR Byte(11)
counter VAR Byte
pos VAR Byte
TempInBits VAR Byte
TempOutBits VAR Byte

' The only reason for using Temp variables, is to address the individual bits in the code below.

Main:
  GOSUB ReadBits

  ' Check Inputs #1
  FOR counter = 0 TO 10
    TempInBits = InBits(counter)
    FOR pos = 0 TO 8 STEP 2
        IF TempInBits.BIT0(pos) = 1 THEN TempOutBits.BIT0(pos) = 1 ' Activate Input #1
    NEXT
    InBits(counter) = TempInBits
  NEXT
  GOSUB WriteBits

  ' WAIT 10 Seconds
  PAUSE 10000

  DO
    ' Check Inputs #2
     GOSUB ReadBits

    FOR counter = 0 TO 10
      TempInBits = InBits(counter)
      TempOutBits = OutBits(counter)
      FOR pos = 0 TO 8 STEP 2
        IF TempInBits.BIT0(pos+1) = 1 THEN  ' Input #2
          TempOutBits.BIT0(pos) = 0   ' Deactivate Input #1
          TempOutBits.BIT0(pos+1) = 1 ' Activate Input #2
        ENDIF
        IF TempInBits.BIT0(pos) = 1 AND TempInBits.BIT0(pos+1)=0 THEN
          TempOutBits.BIT0(pos) = 0 ' Activate Input #1
        ENDIF
      NEXT
      InBits(counter) = TempInBits
      OutBits(counter) = TempOutBits
    NEXT
    GOSUB WriteBits

  LOOP

  END

WriteBits:
  FOR counter = 10 TO 0
    SHIFTOUT iopin, clockpin, MSBFIRST, [noparse][[/noparse]OutBits(counter)]           ' Send the bits to 2nd HC.
  NEXT
  PULSOUT latchpin, 1                                                  ' Transfer to outputs.
  PAUSE 50
  RETURN


ReadBits:
  PULSOUT latchpin, 5 ' Load switch inputs
  FOR counter = 10 TO 0 ' The last HC is read first
    SHIFTIN iopin, clockpin, MSBPRE, [noparse][[/noparse]InBits(counter)] ' shift them in
  NEXT
  PAUSE 50
  RETURN

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Don't worry. Be happy

Drago · 2009-07-17 19:11

Thank you dev/null

It is really easy to confuse me, because as I mentioned I am novice in software development, but you did right.
Thanks one more time.
As soon as I receive my IC’s I will experiment with that and let you know how it works.

BTW: I moved from Europe here recently, and Norway was one of countries I wasn’t able to visit, but I always wish.
Maybe when I get retired (Hi, Hi)
Enjoy!
Drago

dev/null · 2009-07-17 19:13

Maybe I misunderstood a question. Just to assert: You need 3 pins for the 595's and 3 pins for the 165's, for a total of 6 pins.

You are welcome to Norway

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Don't worry. Be happy

dev/null · 2009-07-17 19:18

The code about might not do excactly what you want with regards to your timing issues.
The code will:
1) Read input #1 on all positions, and turn turn outputs #1 ON (if inputs are on)
2) Wait 10 seconds
3) Continously check both inputs. If input #2 is ON, turn Output #1 OFF and Output # 2 ON. If Input #1 is ON and Input #2 is OFF, turn output #1 OFF.

You will probably have to understand the code to make it work perfectly.

Good luck!

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Don't worry. Be happy

Drago · 2009-07-17 19:18

Yes, I will use three pins on BS2 for inputs and other three for outputs.
There are enough pins, so I guess when separate the communication the application should work better and more stabile.
Drago

Chris Savage · 2009-07-17 23:17

Chaining 74HC165 and 74HC595 is covered in detail in the Stamp Works manual and code is included. I often use both devices in design to save I/O pins.

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Chris Savage
Parallax Engineering

WBA Consulting · 2009-07-20 19:53

Drago,
If you would like a hardcopy of the StampWorks 2.0 book, PM me a mailing address. I picked up 5 of them a few years ago on a dirt-cheap eBay auction. Sometimes a hardcopy is easier to use than the PDF. Not sure what the differences are between Version 2.0 and the PDF online that is Version 2.1. I don't see an "change history" anywhere and a quick perusal of both turned up no differences.

I also recently started looking into 595s for a setup that uses multiple Temp/Humidity sensors. I think this may be an easier approach than using up 2 IO pins for each of the 12 sensors.

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Andrew Williams
WBA Consulting
IT / Web / PCB / Audio

Drago · 2009-07-20 20:28

Hi Chris & Andrew,
Thank you for response.
I downloaded already Stamp works and I am fine for now.
It may be somebody else that needs the book more than I.
Dev/null helped me with code and now I am trying to make it work with TPIC6B595 which we already use, but in different configuration.

This should be the same type of shift register, but it allow 150mA of continues current per output instead 35mA (74HC595).
Will se how it will work.
Regards,

Drago

Ron Czapala · 2009-07-26 22:00

The TPIC6B595·and the 74HC595 apparent;y work differently in that the TPIC6B595 (and similar) ICs sink an attached load while the 74HC595 sources a load.
·

Drago · 2009-07-28 17:00

Hi ronczap,
I am not an expert, but I believe that by setting the pin 9 (G) HIGH/LOW that could be changed?

Ron Czapala · 2009-07-28 19:47

I'm no expert either but I wouldn't expect that to work.

Mike Green · 2009-07-28 20:07

The TPIC6B595 works just like a 74HC595 except that the outputs include an open-drain power MOSFET that sinks current (to ground).

The 74HC595 outputs are standard "totem-pole" outputs that will either source current (from Vdd) or sink current (to ground) depending on whether the output state is high or low respectively.

Ron Czapala · 2009-07-28 20:37

Thanks for the info Mike.

Are you saying that the TPIC6B595 can only sink while·the 74HC595 can both·source or sink?

Mike Green · 2009-07-28 20:45

Sort of ...

The TPIC6B595 can only sink current, but can sink quite a bit of it.

The 74HC595 can sink or source current, but not a lot of it (maybe 20mA ... look at the datasheet for details).

Ron Czapala · 2009-07-29 00:31

Mike,

· I just received some 74hc595 shift registers and set up two of them to drive 16 LEDs (per the Stamp Works experiment #23) and everthing works fine. How would I wire the LEDs if I wanted to sink the load rather than source?

I looked up totem-pole outputs but don't grasp the way they function but apparently they can sink more current than they can source.

It would be useful to know how to do that.

Thanks again for your knowledge and help.

Ron

Drago · 2009-07-29 04:17

Shift register TPIC6B595 allow 150mA of continues current per output instead 35mA (74HC595).

Procedure with BS2 & shifters 74HC595 & 74HC165

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