UPD77533 datasheet(27/104 Pages) RENESAS

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Data Sheet S15671EJ4V0DS

µµµµPD77533

The control flow when positioning starts from the receiver side differs depending on the system.

An example of the control flow when positioning starts from the receiver side in a GPS evaluation system is

described below.

When positioning starts from the receiver side, the host CPU sends the

µPD77533 the !cb Request command

(CMD-ID: 0x20). Upon receiving the !cb Request command (CMD-ID: 0x20), the

µPD77533 sends the !cb command

to the LS (location server) following the procedure shown in 16.10 !cb Request. After receiving “!cb”, the LS starts

positioning.

If positioning is requested by the LS, this command does not need to be used.

After receiving the positioning command “$JM” from the LS (host CPU), the

µPD77533 automatically executes the

following processing, as illustrated in Figure 5-1.

1. RF block ON

2. GPS signal reception

3. RF block OFF

4. Pseudo range calculation

5. Calculation result notification

6. Positioning end notification

5.1 Items That Must Be Set Before Start of Positioning

The items that must be set before positioning starts after the GPS module is activated are described below.

5.1.1 Reference frequency

Command: FCC Reference Frequency (CMD-ID: 0x02)

The initial value of the reference clock frequency is 14.4 MHz. To use a reference clock with a frequency of other

than 14.4 MHz, change this setting using the FCC Reference Frequency command (CMD-ID: 0x02).

5.1.2 Frequency adjustment function (FCC)

Command: Frequency Calibration Control (CMD-ID: 0x06)

For details of the frequency adjustment function (FCC: Frequency Calibration Control), see 6.1.1 Frequency

Calibration Control.

The initial value is “No FCC”.

If the

µPD77533 local clock (GPSCLK input clock signal, 16.384 MHz) is not accurate enough, in other words, to

use the reference clock (REFCLK input signal) for frequency adjustment, change this setting to “FCC control used”

using the Frequency Calibration Control command (CMD-ID: 0x06).

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