Electronics America 4-Bit Single-Chip Microcomputer User's Manual

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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
Fig. 5-11 Processor Clock Control Register Format
Note When using a calue of f
XX such that 4.19 MHz < fXX ≤ 5.0 MHz, if maximum speed mode : Φ fXX/4 (PCC1, PCC0
= 11) is set as CPU clock frequency, 1 machine cycle is less than 0.95
µ s and the standard minimum value
0.95 µ s is not kept.
Therefore, is this case, PCC1, PCC0 = 11 cannot be set, so it should be used with PCC1, PCC0 = 00 or 10.
As a result, the combination of “f
XX = 4.19 MHz, PCC1, PCC0 = 11” is maximum speed selection (1 machin
cycle = 0.95
µ s) as CPU clock.
3210 Symbol
FB3H PCC3 PCC2 PCC1 PCC0 PCC
CPU clock selection bits when fXX ≤ 4.19 MHz
( ) : When fXX = 4.19 MHz
CPU Clock Frequency 1 Machine Cycle
00 Φ Output = fXX/64 (65.5 kHz) 15.3 µ s
0 1 Setting prohibited –
10 Φ = fXX/8 (524 kHz) 19.1 µ s
11 Φ = fXX/4 (1.05 MHz) 0.95 µ s
When 4.19 MHz < fXX ≤ 5.0 MHz
( ) : When fXX = 4.19 MHz
CPU Clock Frequency 1 Machine Cycle
00 Φ Output = fXX/64 (76.7 kHz) 13 µ s
0 1 Setting prohibited –
10 Φ = fXX/8 (614 kHz) 1.63 µ s
1 1 Setting prohibited –
fXX : Main system clock oscillation circuit output frequency
CPU operating mode control bit
Address
0 0 Normal operating mode
0 1 HALT mode
1 0 STOP mode
1 1 Setting prohibited