RL78/G10 CHAPTER 12 SERIAL ARRAY UNIT
R01UH0384EJ0311 Rev. 3.11 405
Dec 22, 2016
12.7.5 Calculating transfer rate
The transfer rate for simplified I
2
C (IIC00) communication can be calculated by the following expressions.
(Transfer rate) = {Operation clock (f
MCK) frequency of target channel} ÷ (SDR0nH[7:1] + 1) ÷ 2
Caution SDR0nH[7:1] must not be set to 00000000B. Be sure to set a value of 00000001B or greater for
SDR0nH[7:1]. The duty ratio of the SCL signal output by the simplified I
2
C is 50%. The I
2
C bus
specifications define that the low-level width of the SCL signal is longer than the highlevel
width. If 400 kbps (fast mode) or 1 Mbps (fast mode plus) is specified, therefore, the lowlevel
width of the SCL output signal becomes shorter than the value specified in the I
2
C bus
specifications. Make sure that the SDR0nH[7:1] value satisfies the I
2
C bus specifications.
Remarks 1. The value of SDR0nH[7:1] is the value of bits 7 to 1 of the SDR0nH register (0000001B to
1111111B) and therefore is 1 to 127.
2. n = 0
The operation clock (f
MCK) is determined by serial clock select register 0 (SPS0) and bit 7 (CKS0n) of serial mode
register 0nH (SMR0nH).
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