Renesas rl78 User Manual
RL78/G1A
CHAPTER 12 SERIAL ARRAY UNIT
R01UH0305EJ0200 Rev.2.00
499
Jul 04, 2013
12.5.8 Calculating transfer clock frequency
The transfer clock frequency for 3-wire serial I/O (CSI00, CSI01, CSI10, CSI11, CSI20, CSI21) communication can be
calculated by the following expressions.
(1) Master
(Transfer clock frequency) = {Operation clock (f
MCK
) frequency of target channel} ÷ (SDRmn[15:9] + 1)
÷ 2 [Hz]
(2) Slave
(Transfer clock frequency) = {Frequency of serial clock (SCK) supplied by master}
Note
[Hz]
Note The permissible maximum transfer clock frequency is f
MCK
/6.
Remark The value of SDRmn[15:9] is the value of bits 15 to 9 of serial data register mn (SDRmn) (0000000B to
1111111B) and therefore is 0 to 127.
The operation clock (f
MCK
) is determined by serial clock select register m (SPSm) and bit 15 (CKSmn) of serial mode
register mn (SMRmn).