st20-gp1 STMicroelectronics, st20-gp1 Datasheet - Page 14

• Manufacturer Part Number: st20-gp1
• Description: Gps Processor
• Manufacturer: STMicroelectronics

ST20-GP1
PRNcode0-11 registers
The PRNcode0-11 registers choose the code for the particular satellite, and writing these causes a
reset to the accumulated carrier phase in the NCO for the corresponding channel, if enabled by the
DSPControl register.
The bit-fields for selecting particular GPS satellites are given in Table 3.3.
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DSPControl
Bit
1:0
2
3
PRNcode0-11
Bit
6:0
Bit field
SampleRate
NCOResetEnable
PRNDisable
Bit field
PRNcode
Satellite ID
10
11
12
13
14
15
1
2
3
4
5
6
7
8
9
DSP base address + #140
DSP base address + #00 to #2C
Function
Satellite code as a 7-bit value.
Table 3.2 PRNcode0-11 register format
Function
These bits control the sampling rate (the rate at which data is sent to the DMA
controller). The encoding of these bits is as follows:
When set to 1, the accumulated NCO phase for a channel is reset when the corre-
sponding PRN code register is written.
When set to 1, all PRN generators are disabled.
Table 3.3 PRNcode0-11 register value
Table 3.1 DSPControl register format
SampleRate[1:0]
PRNcode0-11
register value
00
01
10
11
#62
#73
#04
#15
#11
#22
#01
#12
#23
#32
#43
#65
#76
#07
#18
Transfer period
840 s
970 s
31 s
62 s
Taps selected from G2 shift register
by bits 6 to 4
10
10
6
7
8
9
9
8
9
3
4
6
7
8
9
No. of samples
accumulated
256
256
16
8
by bits 3 to 0
2
3
4
5
1
2
1
2
3
2
3
5
6
7
8
Mode
Tracking
Acquisition
a
Write only
Write only