M16C62_M Datasheet, PDF (417/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

UART
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
2.5.6 Clock Signals in used for the SIM Interface
In conforming to the SIM interface, the UART clock signal within the SIM card needs to conform to the
UART2 clock signal within the microprocessor. Two examples are given here as means of generating a
UART2 clock signal within the microprocessor.
* In the case of setting a value equal to or less than (1/256 X 1/16) in the division rate of UART2 clock
Choose f1 for the UART’s source clock signal and set an optional value in the bit rate generator.
* In the case of setting a value equal to or greater than (1/256 X 1/16) in the division rate of UART2 clock
Set the bit rate generator to "0", turn the source clock signal to timer output and set an optional value
in the timer. In order to maintain the synchronization, the serial I/O mode select bits must be reset to
“0002”, then the UART2 transmit/receive mode register is set back to the original setting at every
one byte transmission.
Let F be the clock signal within the SIM card and D be the bit rate adjustment factor, then the formula for
the UART clock signal becomes as follows. Figure 2.5.20 shows an example of connection.
• In the case of setting a value equal to or less than (1/256 X 1/16) in the division rate of UART2 clock
UART2 clock signal within microprocessor = UART clock within SIM card
1
f1 x _{Bit rate generator + 1}
1
1
1
x ₁₆ = f1 x _{Timer Ai counter + 1} x flip-flop x _F/D
Let XIN = 16 MHz, timer Ai counter = 1, F = 372, and D = 1, then the value to be set in the bit rate
generator becomes
1
16 x _{Bit rate generator + 1}
1
11
1
x ₁₆ =16 x ₂ x ₂ x _372/1
Bit rate generator = 92
Table 2.5.8 shows an example of setting in the UART2 bit rate generator.
• In the case of setting a value equal to or greater than (1/256 X 1/16) in the division rate of UART2 clock
UART2 clock signal within microprocessor = UART clock within SIM card
1
1
f1 x _{Timer Aj counter + 1} x flip-flop x _{Bit rate generator + 1}
= f1 x
Bit
rate
1
generator
+
1
x
flip-flop
x
1
F/D
1
x ₁₆
Let XIN= 16 MHz, timer Ai counter = 3, bit rate generator = 0, F = 1860, and D = 1, then the value to be
set in the timer Aj counter becomes
1
11
1
11
1
16 x _{Timer Aj counter + 1} x ₂ x _{0 + 1} x ₁₆
=16 x
x
3+1
2x
1860/1
Timer Aj counter = 464
Table 2.5.9 shows an example of setting in the timer Aj counter.
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