DS89C420-QCL Datasheet, PDF (22/139 Pages) Maxim Integrated Products – Ultra-High-Speed Flash Microcontroller User’s Guide

T2M
Bit 5
T1M
Bit 4
T0M
Bit 3
MD2, MD1, MD0
Bits 2, 1, 0
Ultra-High-Speed Flash
Microcontroller User’s Guide
Watchdog Interrupt Flag Timeout Periods (in Oscillator Clocks)
4X / 2X
1
0
X
X
X
CD1:0
00
00
01
10
11
WD1:0 = 00
2¹⁵
2¹⁶
2¹⁷
2¹⁷
2²⁷
WD1:0 = 01
2¹⁸
2¹⁹
2²⁰
2²⁰
2³⁰
WD1:0 = 10
2²¹
2²²
2²³
2²³
2³³
WD1:0 = 11
2²⁴
2²⁵
2²⁶
2²⁶
2³⁶
Timer 2 Clock Select. This bit controls the input clock that drives Timer 2. This bit has no effect
when the timer is in baud rate generator or clock output modes. See Timer Operation table.
Timer 1 Clock Select. This bit controls the input clock that drives Timer 1. See Timer Operation table.
Timer 0 Clock Select. This bit controls the input clock that drives Timer 0. See Timer Operation table.
Timer Operation (in Oscillator Clocks)
4X/2X CD1:0
1
00
0
00
X
01
X
10
X
11
OSCILLATOR CLOCKS
PER TIMER (0, 1, 2) CLOCK
TxMH, TxM =
00
12
12
12
12
3072
01
1
2
4
4
1024
1X
0.25
0.5
1
1
1024
OSCILLATOR CLOCKS PER
TIMER 2 CLOCK (BAUD RATE GEN)
T2MH, T2M =
XX
2
2
2
2
2048
Stretch MOVX Select 2-0. These bits select the time by which external MOVX cycles are to be
stretched. This allows slower memory or peripherals to be accessed without using ports or manual
software intervention. The RD or WR strobe is stretched by the specified interval, which is transparent
to the software except for the increased time to execute to MOVX instruction. All internal MOVX
instructions are executed at the two machine cycle rate (0 stretch) independent of these bit settings.
MOVX Instruction
MD2, MD1, MD0
000
001
010
011
100
101
110
111
STRETCH VALUE
0
1
2
3
4
5
6
7
MOVX DURATION
2 machine cycles
3 machine cycles
(default)
4 machine cycles
5 machine cycles
9 machine cycles
10 machine cycles
11 machine cycles
12 machine cycles
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