3-64
DSP56367
MOTOROLA
Specifications
Serial Host Interface (SHI) I
2
C Protocol Timing
6
×
T
C
(if HDM[7:0] = $02 and HRS = 1)
to
4096
×
T
C
(if HDM[7:0] = $FF and HRS = 0)
The programmed serial clock cycle (T
I
2
CCP
), SCL rise time (T
R
), and the filters selected
should be chosen in order to achieve the desired SCL serial clock cycle (T
SCL
), as shown in
Table 3-21.
EXAMPLE:
For DSP clock frequency of 120 MHz (i.e. T
C
= 8.33ns), operating in a standard mode I
2
C
environment (F
SCL
= 100 kHz (i.e. T
SCL
= 10
µ
s), T
R
= 1000ns), with wide filters enabled:
T
I
2
CCP
= 10
µ
s - 2.5
×
8.33ns - 223ns - 1000ns = 8756ns
Choosing HRS = 0 gives
HDM[7:0] = 8756ns / (2
×
8.33ns
×
8) - 1 = 64.67
Thus the HDM[7:0] value should be programmed to $41 (=65).
The resulting T
I
2
CCP
will be:
T
I
2
CCP
= [T
C
×
2
×
(HDM[7:0] + 1)
×
(7
×
(1 – HRS) + 1)]
T
I
2
CCP
= [8.33ns
×
2
×
(65 + 1)
×
(7
×
(1 – 0) + 1)]
T
I
2
CCP
= [8.33ns
×
2
×
66
×
8] = 8796.48ns
Table 3-21 SCL Serial Clock Cycle (T
SCL
) Generated as Master
Filters bypassed
T
I
2
CCP
+ 2.5
×
T
C
+ 45ns +
T
R
Narrow filters enabled
T
I
2
CCP
+ 2.5
×
T
C
+ 135ns +
T
R
Wide filters enabled
T
I
2
CCP
+ 2.5
×
T
C
+ 223ns +
T
R
Summary of Contents for DSP56367
Page 16: ...xvi MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 22: ...xxii MOTOROLA List of Figures Figure Number Title Page Number ...
Page 26: ...xxvi MOTOROLA List of Tables Table Number Title Page Number ...
Page 148: ...4 6 DSP56367 MOTOROLA Design Considerations PLL Performance Issues ...
Page 248: ...9 30 DSP56367 MOTOROLA Serial Host Interface SHI Programming Considerations ...
Page 306: ...10 58 DSP56367 MOTOROLA Enhanced Serial Audio Interface ESAI ESAI Initialization Examples ...
Page 389: ...Bootstrap ROM Contents MOTOROLA DSP56367 A 15 end ...
Page 390: ...A 16 DSP56367 MOTOROLA Bootstrap ROM Contents ...
Page 432: ...C 8 DSP56367 MOTOROLA JTAG BSDL ...
Page 484: ...D 52 DSP56367 MOTOROLA Programmer s Reference ...
Page 490: ...E 6 DSP56367 MOTOROLA Power Consumption Benchmark ...
Page 516: ...F 26 DSP56367 MOTOROLA IBIS Model ...
Page 522: ...Index 6 MOTOROLA Index ...
Page 523: ......