Renesas SH7781 - Manual (Page 1187)

23. Serial Peripheral Interface (HSPI)
Rev.1.00 Jan. 10, 2008 Page 1157 of 1658
REJ09B0261-0100
The serial clock frequency can be computed using the following formula:
Peripheral clock frequency
(Initial division ratio × (Clock division count + 1) × 2)
Serial clock frequency =
When the HSPI is configured as a slave, the IDIV and CLKC bits are ignored and the HSPI
synchronizes to the externally supplied serial clock. The maximum value of the external serial
clock that the module can operate with is Pck / 8.
If any of the FBS, CLKP, IDIV or CLKC bit values are changed, the HSPI will undergo a
software reset.
When IPIV or CLKC is specified or changed, the internal serial clock generation counter is reset.
In this case, data transmit/receive should be performed after the time length of at least one serial
clock cycle (depends on IDIV or CLKC specified) has elapsed.