TMP86C845UG Datasheet, PDF (98/136 Pages) Toshiba Semiconductor – 8 Bit Microcontroller

9. Synchronous Serial Interface (SIO)
9.3 Function
TMP86C845UG
9.3 Function
9.3.1 Serial clock
9.3.1.1 Clock source
The serial clock can be selected by using SIOCR1<SCK>. When the serial clock is changed, the writing
instruction to SIOCR1<SCK> should be executed while the transfer is stopped (when SIOSR<SIOF>
“0”)
(1) Internal clock
Setting the SIOCR1<SCK> to other than “111B” outputs the clock (shown in " Table 9-1 Serial
Clock Rate (fc = 16 MHz, fs = 32.768kHz) ") as serial clock outputs from SCK pin. At the before
beginning or finishing of a transfer, SCK pin is kept in high level.
When writing (in the transmit mode) or reading (in the receive mode) data can not follow the serial
clock rate, an automatic-wait function is executed to stop the serial clock automatically and hold the
next shift operation until reading or writing is completed (shown in " Figure 9-2 Automatic-wait
Function (Example of transmit mode) "). The maximum time from releasing the automatic-wait
function by reading or writing a data is 1 cycle of the selected serial clock until the serial clock comes
out from SCK pin.
SIOCR1<SIOS>
SCK pin output
SO pin
SIOTDB
Automatically wait
A7 A6 A5 A4 A3 A2 A1 A0
A
B7 B6 B5 B4 B3 B2 B1 B0
B
Automatic wait is released by writing SIOTDB
Figure 9-2 Automatic-wait Function (Example of transmit mode)
Table 9-1 Serial Clock Rate (fc = 16 MHz, fs = 32.768kHz)
SCK
000
001
010
011
100
101
110
NORMAL1/2, IDLE1/2 Mode
TBTCR<DV7CK> = "0"
TBTCR<DV7CK> = "1"
Serial Clock
Baud Rate
Serial Clock
Baud Rate
fc/2¹²
3.906 kbps
fs/2⁴
2048 bps
fc/2⁸
62.5 kbps
fc/2⁸
62.5 kbps
fc/2⁷
125 kbps
fc/2⁷
125 kbps
fc/2⁶
250 kbps
fc/2⁶
250 kbps
fc/2⁵
500 kbps
fc/2⁵
500 kbps
fc/2⁴
1.00 Mbps
fc/2⁴
1.00 Mbps
fc/2³
2.00 Mbps
fc/2³
2.00 Mbps
SLOW1/2, SLEEP1/2 Mode
Serial Clock
Baud Rate
fs/2⁴
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
2048 bps
–
–
–
–
–
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