Latching and configuring inputs.

[john green]

Another two questions from a struggling learner.

I am using a 28X1 (Why? Because it’s what came fitted to my starter pack!)

With comparative ease, I managed to write a program to control a two way traffic light sequence but on trying to introduce a pedestrian crossing, found myself pulling hair out in clumps in trying to include a latched signal such that pressing a button would hold a notification in abeyance until the sequence reaches a logical point to give the pedestrians right of way, ie. when both roads have a red light.

I discovered how to use an interrupt which almost achieved this end but which failed the test of being a workable solution because, as might well be expected, it interrupted the ongoing sequence at the moment of the pedestrian request.
A functional solution, used just to prove the reminder of the program, was using an external logic gate as a latch and this works perfectly.
So, question 1). Is there a way of getting an input that may appear at anytime during a sequence, to latch without disturbing the ongoing program or using external components? This of course also has to be cancelled after each operational cycle.

This is the working code using the external latch.

;traffic lights with single ped crossing
;RYGRYGRYleds on Bout0-7
;latch 14066 on from +5v push button
;off from pull down port c7
;latch high = green man LED read on ADC3 




main:

      
	
	
	
	readadc 3,b1


one:
	high 1
	high 7            ;red A 
	high 4            ;red B
	pause 1000
	high 7            ;red A
	high 6            ;yellow A 
	high 4            ;red B
	pause 1500
	low 7             ;off red A
	low 6             ;off yellow A  
	high 5            ;green A    
	high 4            ;red B
	pause 5000
      low 5             ;off greenA
      high 6            ;yellow A 
	high 4            ;red B
	pause 2000
      low 6		      ;off yellow A	
      high 7            ;red A 
      high 4            ;red B 
      pause 500
	
	readadc 3,b1
	if b1 >100 then goto cross1:
	
	if b1 <100 then goto two:
	
two: 
	high 1
	high 4            ;red A 
	high 7            ;red B
	pause 1000
	high 4            ;red B
	high 3            ;yellow B 
	high 7            ;red A
	pause 1500
	low 4             ;off red B
	low 3             ;off yellow B  
	high 2            ;green B    
	high 7            ;red A
	pause 5000
	low 2             ;off greenB
      high 3            ;yellow B 
	high 7            ;red A
	pause 2000
      low 3		      ;off yellow B	
      high 7            ;red A 
      high 4            ;red B 
      
      pause 500
 	readadc 3,b1
      if b1 > 100 then goto cross2:
	
	if b1 <100 then goto main:
	
	



cross1:

	high 4     	      ;red B
	high 7	      ;red A	
	pause 1000      
	low 1             ;off red man
	high portc 7      ;turn latch off 
	pause 100
	low portc 7       ;off cancel latch
	high 0            ;on walk signal
	pause 4000
	low 0             ;off walk signal
	for b0 = 1 to 10  ;flash walk signal,loop 10 times
	high 0            ;switch on output 0
	pause 200         ;wait 0.2 seconds
	low 0             ;switch off output 0
	pause 200         ;wait 0.2 seconds
	next b0           ;end of loop
	low 0             ;off walk signal 
	high 1            ;on red man
	pause 2000
      
	
	goto two:	
	
cross2:

	high 7		;red A
	high 4		;red B	
	pause 1000
	low 1             ;off red man  
	high portc 7      ;cancel latch
	pause 100
	low portc 7       ;off cancel latch
	high 0            ;on walk signal
	pause 4000
	low 0			;off walk signal 	 
	for b0 = 1 to 10  ;flash walk signal,loop 10 times
	high 0            ; switch on output 0
	pause 200         ; wait 0.2 seconds
	low 0             ; switch off output 0
	pause 200         ; wait 0.2 seconds
	next b0           ; end of loop
	high 1            ;on red man
	low 0
	pause 2000
	
	
	goto main:

Question 2).

Wanting to identify the latch being ‘high’ and a digital rather than analogue input being needed, I tried to re configure the C1 port to be an input rather than output and get a value to store at b1. Having tried and failed with let dirsc = %00000010, I copied and pasted directly from the manual;

To convert all the pins to inputs
let dirsc = %00000000

However, then using

read pinc.1,b1

…the instruction was accepted by the simulator but was unaffected by trying to simulate any value on the input and I could not get b1 to change from 0.
Not surprisingly, it also failed to achieve anything when run in the real circuit.

I also tried

readadc C.1,b1

…but even though this was copied and pasted direct from the manual, the simulator responds with Error: Unknown symbol - C.1

Can you please advise how to achieve both configuring those pins to inputs and then, how best to get that value stored somewhere useful - like b1?


Thanks....

 

[MartinM57]

I think

b1 = pinc.1

...is the light bulb moment you are looking for. "read" is an entirely different command.

 

[hippy]

Note that interrupt will cause any currently executing PAUSE to be prematurely terminated, so it's best to do the interval timing between lights as a number of loops of a shorter PAUSE. That can be put into a subroutine for easier use ...

Pause 1500

can become ...

w0 = 1500 : Gosub PauseForSomeTime

PauseForSomeTime:
For w1 = 0 To w0 Step 100
Pause 100
Next
Return

On the 28X2 it would be even easier to use the HINTSETUP commands and the 'hintXflag' variables to latch a button push but that is not available for the 28X1.