
20
20-3
Rev.1.0
OSCILLATION CIRCUIT
20.1 Oscillator Circuit
20.1.2 System Clock Output Function
A clock whose frequency is twice the input frequency can be output from the BCLK pin. The BCLK
pin is shared with port P70. When you use this pin to output the system clock, set the P7 Operation
Mode Register (P7MOD)'s D8 bit to 1. Configuration of the P7 Operation Mode Register is shown
below.
s P7 Operation Mode Register (P7MOD)
<Address: H'0080 0747>
D8
9
10111213
14
D15
P70MOD P71MOD P72MOD P73MOD P74MOD P75MOD P76MOD P77MOD
<When reset : H'00>
D
Bit Name
Function
R
W
8
P70MOD
0 : P70
(Port P70 operation mode)
1 : BCLK
9
P71MOD
0 : P71
(Port P71 operation mode)
____
1 : WAIT
10
P72MOD
0 : P72
(Port P72 operation mode)
____
1 : HREQ
11
P73MOD
0 : P73
(Port P73 operation mode)
____
1 : HACK
12
P74MOD
0 : P74
(Port P74 operation mode)
1 : RTDTXD
13
P75MOD
0 : P75
(Port P75 operation mode)
1 : RTDRXD
14
P76MOD
0 : P76
(Port P76 operation mode)
1 : RTDACK
15
P77MOD
0 : P77
(Port P77 operation mode)
1 : RTDCLK