Clock External Output (Fout3, Fout1) - Epson S1C17001 Technical Manual

7.6 Clock External Output (FOUT3, FOUT1)

The OSC3 division clock (FOUT3) and OSC1 clock (FOUT1) can be output to devices outside the chip.
OSC3 clock
OSC1 clock
FOUT3 output
FOUT3 is the OSC3 division clock.
Output pin setting
The FOUT3 output pin is combined with the P30 port. This functions as the P30 port pin by default, so the
pin function should be changed by writing 1 to P30MUX (D0/P3_PMUX register) if use is required for
FOUT3 output.
∗ P30MUX: P30 Port Function Select Bit in the P3 Port Function Select (P3_PMUX) Register (D0/0x52a3)
FOUT3 clock frequency selection
Three different clock output frequencies can be selected. Select the division ratio for the OSC3 clock using
FOUT3D[1:0] (D[3:2]/OSC_FOUT register).
∗ FOUT3D[1:0]: FOUT3 Clock Division Ratio Select Bits in the FOUT Control (OSC_FOUT) Register
Clock output control
The clock output is controlled using the FOUT3E (D1/OSC_FOUT register). Setting FOUT3E to 1 outputs
the FOUT3 clock from the FOUT3 pin. Setting it to 0 halts output.
∗ FOUT3E: FOUT3 Output Enable Bit in the FOUT Control (OSC_FOUT) Register (D1/0x5064)
Note: Since the FOUT3 signal is asynchronized with FOUT3E writing, switching output on or off will
generate certain hazards.
S1C17001 TECHNICAL MANUAL
Division circuit
(1/1 to 1/4)
Division ratio selection
Figure 7.6.1: Clock output circuit
(D[3:2]/0x5064)
Table 7.6.1: FOUT3 clock division ratio selection
FOUT3D[1:0]
0x3
0x2
0x1
0x0
FOUT3E 0
FOUT3 output (P30)
Figure 7.6.2: FOUT3 output
P30 port
FOUT3
Output circuit
On/off control P30 function selection
P13 port
FOUT1
Output circuit
On/off control P13 function selection
Division ratio
Reserved
OSC3-1/4
OSC3-1/2
OSC3-1/1
(Default: 0x0)
1
EPSON
7 OSCILLATOR CIRCUIT (OSC)
FOUT3(P30)
FOUT1(P13)
0
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