Eliminating use of PulseOut from AN220 - Parallel LCD

[mikep]

Application note AN220 is "Interfacing a Parallel LCD". For native mode devices it is possible to eliminate the use of PulseOut() and therefore remove the dependency on a timer, freeing it up for another use.

The trick is to use the new library functions recently introduced named DelayMicroseconds() and DelayMilliseconds(). This works because a LockTask is used so any busy loops would occur in any case. The functions PinHigh() and PinLow() can also be used to improve performance a little when outside the timing delay. The attached code shows the before and after for each code snippet. The actual changes are left as an exercise to the reader (!).

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'Before
Private Const ePulseWidth as Single = 5.0e-5
'After
Private Const ePulseWidth as Integer = 50  '50 microseconds

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'Before
Call PulseOut(pinE, ePulseWidth, 1)
'After
Call PinHigh(pinE)
Call DelayMicroseconds(ePulseWidth)
Call PinLow(pinE)

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'Before
Call PulseOut(0, 5.0e-3, 0)
'After
Call DelayMilliseconds(5)

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'Before
Call PulseOut(0, 0.2e-3, 0)	' 200uS delay
'After
Call DelayMicroseconds(200)	' 200us delay

There is a LockTask()/UnlockTask() pair around the critical timing of the output code in DisplayCharAt and DisplayStrAt. Although not shown in the example code, this should also be added to critical code the InitLCD() subroutine for safety