
SP37
Tire Pressure Monitoring Sensor
ROM Library Functions
ROM Library Function Guide
81
Revision 1.0, 2011-12-15
2.18
VCO_Tuning()
2.18.1
Description
This function selects an appropriate tuning curve for the VCO and enables the PLL. If no proper tuning curve could
be selected the PLL will be disabled before the function returns with an error result.
Notes
1. If RF transmission is not performed immediately after this function is called, it is recommended to disable the
PLL by clearing SFR bit RFC.1[ENPLL] to reduce the current consumption.
2. Re-Calibration of the tuning curve is necessary when
V
BAT
changes more than 800mV or
T
Ambient
changes more
than 70 °C
2.18.2
Actions
•
Select appropriate tuning curve
•
Enable PLL for a RF transmission
•
Wait until PLL is locked
2.18.3
Prototype
signed char
VCO_Tuning
(void)
2.18.4
Inputs
2.18.5
Outputs
VCO_Tuning: Output values
Table 82
VCO_Tuning: Input Parameters
Register / Address
Type
Name
Description
None
void
---
---
Register/ Address
Type
Name
Description
R7
signed char
StatusByte
StatusByte:
0: Success of VCO Tuning
-1: VCO Tuning not successful, PLL disabled
-2: XTAL not enabled (crystal required)