ADSP-2126x SHARC Processor Hardware Reference
9-63
Serial Ports
The
CLKDIV
bit field specifies how many times the processor’s internal
clock (
CCLK
) is divided to generate the transmit and receive clocks. The
frame sync (
SPORTx_FS
) is considered a receive frame sync if the data sig-
nals are configured as receivers. Likewise, the frame sync
SPORTx_FS
is
considered a transmit frame sync if the data signals are configured as
transmitters. The divisor is a 15-bit value, allowing a wide range of serial
clock rates.
Use the following equation to calculate the serial clock frequency:
The maximum serial clock frequency is equal to one-quarter the proces-
sor’s internal clock (
CCLK
) frequency, which occurs when
CLKDIV
is set to
zero. Use the following equation to determine the value of
CLKDIV
, given
the
CCLK
frequency and desired serial clock frequency:
The bit field
FSDIV
specifies how many transmit or receive clock cycles are
counted before a frame sync pulse is generated. In this way, a frame sync
Figure 9-8. DIVx Register
f
SPORTx_CLK
= f
CCLK
4(1)
4(f
SPORTx_CLK
)
f
CCLK
– 1
CLKDIV =
31 30
29 28 27 26
24
23 22
21 20
19
18 17 16
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
FSDIV
15 14
13 12 11 10
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CLKDIV
Clock Divisor
25
9
Frame Sync Divis
Reserved
DIV0 (0xC02)
DIV1 (0xC03)
DIV2 (0x402)
DIV3 (0x403)
DIV4 (0x802)
DIV5 (0x803)
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...