Epson S1C6200A Specifikace stáhnout pdf (Strana 210)

II-58 EPSON S1C62740 TECHNICAL SOFTWARE

CHAPTER 6: PERIPHERAL CIRCUITS (SVD Circuit)

Example program

for the SVD circuit

Following program shows the SVD controlling procedure.

Label Mnemonic/operand Comment

;* SVD (FOR OSC1 OPERATION)

ZSVDC EQU 0FFH ;SVD CONTROL REGISTER

;

SCDCHK:

LD X,ZSVDC

LD MX,0000B ;SET CRITERIA VOLTAGE = 2.6 V

;

OR MX,0001B ;START CHECK SUPPLY VOLTAGE

AND MX,1110B ;TURN OFF SVD

;

LD A,MX ;READ SVD DATA INTO A REGISTER'S BIT 1

RET

;

Programming notes

(1) The SVD circuit should normally be turned OFF (SVDON = "0")

as the consumption current of the IC becomes large when it is

ON (SVDON = "1").

(2) To obtain a stable result, the SVD circuit must be set to ON

with at least 100 µsec. Hence, to obtain the SVD detection

result, follow the programming sequence below.

1. Set SVDON to "1" (ON)

2. Maintain at least 100 µsec minimum

3. Set SVDON to "0" (OFF)

4. Read out SVDDT

However, when a crystal oscillation clock (f

OSC1) is selected for

CPU system clock, the instruction cycle are long enough, so

that there is no need for concern about maintaining 100 µsec

for the SVDON = "1" with the software.

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Epson S1C6200A Specifikace Strana 210