Question on 74HC165 x 2 input switches - Stampworks Experiment 24

T&E Engineer

Refering to the Stampworks experiment 24 with the 74HC165 cascaded input circuit....

The input switches provide (2) Byte (or 1 Word) but in this case I modified it for (2) Bytes for each 8 input switches.

Everything said it is working correctly.

My question is that I want to be able to "capture" or "latch in" 3 pushbutton sequences and store it probably as 3 separate bytes.

I'm not sure what approach to try such as polling or something else??


In other words, I press the 3rd pushbutton and I want to store the binary code %00000011 in a Byte such as "Digit100s". Then the second time I hit another pushbutton (lets say the 5th pushbutton) I want to store the binary code %00000101 in a Byte such as "Digit10s". Finally the 3rd time I press on a pushbutton (lets say the 8th pushbutton) I want to store the binary code %00001000 in a Byte such as "Digit1s".

Does anyone have experience with something like this?

If I think about it long enough I can come up with something. However, I am a believer in not re-inventing the wheel. To gain knowledge to learn from is the first step in sharing it for those in need.

I would appreciate any comments.

Thanks,

Timothy Gilmore

T&E Engineer

Here is what I came up with if anyone is interested:

(It doesn't use the 74HC165 as I was not able to get that working right)

=====================================================

' ButtonTest.BS2
' Written by Timothy Gilmore
' December 31st, 2005


' {$STAMP BS2}
' {$PBASIC 2.5}

Btn0··········· PIN···· 0
Btn1··········· PIN···· 1
Btn2··········· PIN···· 2
Btn3··········· PIN···· 3
Btn4··········· PIN···· 4
Btn5··········· PIN···· 5
Btn6··········· PIN···· 6
Btn7··········· PIN···· 7
Btn8··········· PIN···· 8
Btn9··········· PIN···· 9

'

---

' Constants
'

---

'

---

' Variables
'

---

btnWrk0········ VAR···· Byte
btnWrk1········ VAR···· Byte
btnWrk2········ VAR···· Byte
btnWrk3········ VAR···· Byte
btnWrk4········ VAR···· Byte
btnWrk5········ VAR···· Byte
btnWrk6········ VAR···· Byte
btnWrk7········ VAR···· Byte
btnWrk8········ VAR···· Byte
btnWrk9········ VAR···· Byte

Value············ VAR···· Byte
Digit100s········VAR···· Byte
Digit10s········· VAR···· Byte
Digit1s··········· VAR···· Byte
Total············· VAR···· Byte

'

---

' Initialization
'

---

Initialize:

'

---

' Program Code
'

---

Main:

GOSUB Get3Buttons······· 'Get all·3 digits from pushbuttons

DEBUG DEC Digit100s ···· 'Display in DEBUG window 100's digit
DEBUG DEC Digit10s
DEBUG DEC Digit1s

Total = (Digit100s * 100) + (Digit10s * 10) + Digit1s······'Add them up

' More code here ....




DEBUG CLRDN, CR········· 'Clear the DEBUG window for next 3 digits to be displayed

GOTO Main··············· 'Repeat process

'

---

' Subroutines
'

---

Get3Buttons:
·Value = 255
·GOSUB GetButtons
·Digit100s = Value
·Value = 255
·GOSUB GetButtons
·Digit10s = Value
·Value = 255
·GOSUB GetButtons
·Digit1s = Value
·RETURN


GetButtons:
Button0:
· PAUSE 5
· BUTTON Btn0, 0, 200, 20, btnWrk0, 0, Button1
· Value = 0

Button1:
· PAUSE 5
· BUTTON Btn1, 0, 200, 20, btnWrk1, 0, Button2
· Value = 1

BUTTON2:
· PAUSE 5
· BUTTON Btn2, 0, 200, 20, btnWrk2, 0, Button3
· Value = 2

BUTTON3:
· PAUSE 5
· BUTTON Btn3, 0, 200, 20, btnWrk3, 0, Button4
· Value = 3

BUTTON4:
· PAUSE 5
· BUTTON Btn4, 0, 200, 20, btnWrk4, 0, Button5
· Value = 4

BUTTON5:
· PAUSE 5
· BUTTON Btn5, 0, 200, 20, btnWrk5, 0, Button6
· Value = 5

BUTTON6:
· PAUSE 5
· BUTTON Btn6, 0, 200, 20, btnWrk6, 0, Button7
· Value = 6

BUTTON7:
· PAUSE 5
· BUTTON Btn7, 0, 200, 20, btnWrk7, 0, Button8
· Value = 7

BUTTON8:
· PAUSE 5
· BUTTON Btn8, 0, 200, 20, btnWrk8, 0, Button9
· Value = 8

BUTTON9:
· PAUSE 5
· BUTTON Btn9, 0, 200, 20, btnWrk9, 0, No_Press
· Value = 9


No_Press:
IF Value = 255 THEN
· GOTO Button0
ENDIF
RETURN

======================================================

Jon Williams

If you're looking to capture 24 inputs with the '165 it's simply a matter of daisy-chaining a third chip -- then you would update the scan routine as follows:

Get_XInputs:
· PULSOUT Load, 5
· SHIFTIN SerData, Clock, MSBPRE, [noparse][[/noparse]xIn1, xIn2, xIn3]
· RETURN

... where xIn1, xIn2, and xIn3 are defined as bytes; xIn1 is the 74x165 connected first in the chain (relative to the BASIC Stamp).

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Jon Williams
Applications Engineer, Parallax

Jon Williams

Another note: Using multiple instances of BUTTON is not very efficient; StampWorks experiment #14 demonstrates how to simultaneously debounce and scan mutliple inputs.· I use the Get_Buttons subroutines in a lot of my programs as it's easy to expand -- the target variable can be a Nib (1 to 4 inputs), Byte (up to 8 inputs) or Word (up to 16 inputs).· It's quite flexible and with bit-level aliasing of the input variable can make one's program very easy to work with.

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Jon Williams
Applications Engineer, Parallax