Cmsemicon CMS32L051 - Calculation of the Transmit Clock Frequency

V1.2.2
CMS32L051 User Manual |Chapter 12 Universal Serial Communication Unit
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12.6.4 Calculation of the transmit clock frequency
The transmit clock frequency of the slave select input function (SSPI00) communication can be
calculated using the following calculation formula.
(1) Slave device
Note The maximum enable transmit clock frequency is f
MCK
/6.
Remark m: Unit number (m=0) n: Channel number (n=0) p: SSPI number (p=00)
Table 12-3 Slave select input function run clock selection
SMRmn
register
SPSm register
Run clock (f
MCK
)
Note
CKSmn
PRS
m13
PRS
m12
PRS
m11
PRS
m10
PRS
m03
PRS
m02
PRS
m01
PRS
m00
f
CLK
=32MHz operation
0
X
X
X
X
0
0
0
0
f
CLK
32MHz
X
X
X
X
0
0
0
1
f
CLK
/2
16MHz
X
X
X
X
0
0
1
0
f
CLK
/2
2
8MHz
X
X
X
X
0
0
1
1
f
CLK
/2
3
4MHz
X
X
X
X
0
1
0
0
f
CLK
/2
4
2MHz
X
X
X
X
0
1
0
1
f
CLK
/2
5
1kHz
X
X
X
X
0
1
1
0
f
CLK
/2
6
500kHz
X
X
X
X
0
1
1
1
f
CLK
/2
7
250kHz
X
X
X
X
1
0
0
0
f
CLK
/2
8
125kHz
X
X
X
X
1
0
0
1
f
CLK
/2
9
62.5kHz
X
X
X
X
1
0
1
0
f
CLK
/2
10
31.25kHz
X
X
X
X
1
0
1
1
f
CLK
/2
11
15.63kHz
X
X
X
X
1
1
0
0
f
CLK
/2
12
7.81kHz
X
X
X
X
1
1
0
1
f
CLK
/2
13
3.91kHz
X
X
X
X
1
1
1
0
f
CLK
/2
14
1.95kHz
X
X
X
X
1
1
1
1
f
CLK
/2
15
977Hz
Note To change the clock selected as f
CLK
(change the value of the system clock control register (CKC)), you must
stop the operation of the universal serial communication unit (SCI) (serial channel stop register m(STm)=000FH)
after making the change.
Remark 1.X: Ignore
2.m: Unit number (m=0) n: Channel number (n=0).
(transmit clock frequency) = {Serial clock (SCLK) frequency provided by the master device}
Note
[Hz].