Remote-processing RPC-2350 Manual do Utilizador descarregar pdf (Página 59)

MULTI-MODE COUNTER CHAPTER 14

14-4

Figure 14-2 W7 and W9 jumper detail

HIGH VOLTAGE INPUT

Connector J10, pin 10 can accept a ±15V signal. As

shipped from the factory, it detects a high input level

(output goes low) at about + 3 volts and a low input

(output goes high) at about + 2 volts. This level is

programmable by changing R28.

Lower the value of R28 to incr ease the “ high” level.

For example, changing R28 to 23K raises the high input

level threshold to about 4. 2 volts and the low level to

about 3.2 volts. The thresholds are approximate and

change fr om lot to lot.

The output of the buffer connects to a c ounter inp ut via

jumper W9. When W9 is jumpered it will goto the

counter’s “A” input and to J10-9.

The buffer inver ts the input signal. A count incr ements

when a signal goes “ high to “ low” on this input.

This line is useful for con necting pr oximity sw itches to

the counter. It may be used to filter switch contact

closures by tying a capacitor from its input to ground. A

10K pull-up resistor is connected to the input.

PROGRAMMING

The LS7166 is capable of several operating modes, all of

which cannot be discussed. See Appendix A for this

chips operating modes. What are shown are example of

how to program this chip and some common operating

modes. .

The counter chip must be initialized before using the

COUNT function. You need to write to the ICR (Input

control register), OCCR (Output control register), and

possibly QR (Quadrature register) in order to set up the

counter. Examples are given below for different

operating modes.

The COUNT function returns the current counter value.

Specifically, CAMBASIC writes a 2 to the MCR

(Master Control Register), reads the 3 counter bytes

from the OL (Output latch), and converts it to the proper

internal BASIC for mat.

The LS7166 has several count related registers. The PR

(Preset register ) is a kind of holding register . A bit in

the MCR (Master control register) transfer s the

information to the CNTR (counter). T he PR is used to

pre-load the counter . T his pre-load value can be put into

the main counter by setting a bit in the MCR or bringing

the LCTR (J10-6) line low momentarily.

The CNTR is read by first setting another bit in the

MCR to transfer CNT R to OL (Output latch).

CAM BASIC C OUN T(8) function does this.

The counter is capable of generating an interrupt every

time CNTR equal PR, or when CN TR passes through 0

while counting up or down.

NOTE: Pulses from the LS7166 C Y and BW pins m ust

be long enough for the RPC2350 to recognize

an interrupt. Counting speed is limited to about

100 KHz when interrupts are desired. Even

these can be missed as CAMBASIC shuts off

interrupts at points in the pr ogram , especially

when writing to the graphics screen or Flash.

WARNING:

Do not use the CY or BW pulses to generate an

interrupt in quadrature mode. The pulses are far too

short and are easily missed by hardware. Contact

Remote Processing for solutions.

Program Examples

This code, in CN TR1. BAS, r esets the counter and

enables the inputs. If d esired, connect J2-19 to J10-9 to

see the count increment. The count is printed once a

second. If desired, you can bring J10-9 to another

device.

10 pr "Counter test / demo program"

20 pr "Uses J2-19 to generate pulses."

30 pr "Connect to J10-9 (counter

input)"

40 print "Count continues until there

is an error. (about 16 million)

50 pr "Current count is printed every

second."

100 config pio 0,0,1,1,1,0 :'make

port A output

110 out &f1,32 :'reset counter to 0

120 out &f1,72 :'Enable counter A/B

1 2 ... 54 55 56 57 58 59 60 61 62 63 64 ... 82 83

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