COP620C datasheet(13/26 Pages) NSC

13 / 26 page

Functional Description (Continued)

The program memory is addressed by the 15-bit program

counter (PC). ROM can be indirectly read by the LAID in-

struction for table lookup.

DATA MEMORY

The data memory address space includes on chip RAM, I/O

and registers. Data memory is addressed directly by the in-

struction or indirectly by the B, X and SP registers.

The COP820C family has 64 bytes of RAM and the

COP840C family has 128 bytes of RAM. Sixteen bytes of

RAM are mapped as “registers” that can be loaded immedi-

ately, decremented or tested. Three specific registers: B, X

and SP are mapped into this space, the other bytes are

available for general usage.

The instruction set permits any bit in memory to be set, reset

or tested. All I/O and registers (except the A & PC) are

memory mapped; therefore, I/O bits and register bits can be

directly and individually set, reset and tested.

Note: RAM contents are undefined upon power-up.

RESET

The RESET input when pulled low initializes the microcon-

troller. Initialization will occur whenever the RESET input is

pulled low. Upon initialization, the ports L and G are placed in

the TRI-STATE mode and the Port D is set high. The PC,

PSW and CNTRL registers are cleared. The data and con-

figuration registers for Ports L & G are cleared.

The external RC network shown in

Figure 3 should be used

to ensure that the RESET pin is held low until the power sup-

ply to the chip stabilizes.

OSCILLATOR CIRCUITS

Figure 4 shows the three clock oscillator configurations.

A. CRYSTAL OSCILLATOR

The device can be driven by a crystal clock. The crystal net-

work is connected between the pins CKI and CKO.

Table 1 shows the component values required for various

standard crystal values.

B. EXTERNAL OSCILLATOR

CKI can be driven by an external clock signal. CKO is avail-

able as a general purpose input and/or HALT restart control.

C. R/C OSCILLATOR

CKI is configured as a single pin RC controlled Schmitt trig-

ger oscillator. CKO is available as a general purpose input

and/or HALT restart control.

Table 2I shows the variation in the oscillator frequencies as

functions of the component (R and C) values.

OSCILLATOR MASK OPTIONS

The device can be driven by clock inputs between DC and

10 MHz.

TABLE 1. Crystal Oscillator Configuration, T

A = 25˚C

Ω)

(pF)

CKI Freq

(MHz)

Conditions

30–36

CC =5V

30–36

CC =5V

200

100–150

0.455

CC =5V

TABLE 2. RC Oscillator Configuration, T

A = 25˚C

Ω)

(pF)

CKI Freq.

(MHz)

Instr. Cycle

(µs)

Conditions

3.3

2.2 to 2.7

3.7 to 4.6

CC =5V

5.6

100

1.1 to 1.3

7.4 to 9.0

CC =5V

6.8

100

0.9 to 1.1

8.8 to 10.8

CC =5V

Note 19: 3k

≤ R ≤ 200k, 50 pF ≤ C ≤ 200 pF

DS009103-9

≥ 5X Power Supply Rise Time

FIGURE 3. Recommended Reset Circuit

DS009103-10

FIGURE 4. Crystal and R-C Connection Diagrams

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