Hirc_Clock_Check(); Description; Actions; Prototype - Infineon SP37 Function Manual

2.35

HIRC_Clock_Check()

2.35.1

Description

This function measures the frequency of the 12 MHz RC Oscillator, using the crystal oscillator as a measurement
standard. It evaluates whether the 12 MHz RC Oscillator is working in the specified range (see [1]).
The crystal oscillator is automatically started, if not already enabled, and allowed a fixed startup time of
approximately 2.5ms (five 2 kHz RC LP Oscillator periods). The crystal frequency divided by 2 has to be stored in
the FLASH user configuration sector at address 57FA
FLASH location is not within the range of 9 MHz to 10 MHz a default clock frequency of 9.843750 MHz is assumed
for the checking. Before the function returns the previous clock settings are restored.
2.35.2

Actions

• Check the frequency of the 12 MHz RC Oscillator using the crystal oscillator as measurement standard
2.35.3

Prototype

signed char HIRC_Clock_Check(void)
2.35.4

Inputs

Table 149 HIRC_Clock_Check: Input Parameters
Register / Address
None
2.35.5

Outputs

Table 150 HIRC_Clock_Check: Output values
Register/ Address
R7
ROM Library Function Guide
Type Name
--- ---
Type Name
signed char Statusbyte
Tire Pressure Monitoring Sensor
(MSByte) to 57FC
H H
Description
---
Description
0: success
-1: 12 MHz RC Oscillator out of specified range
-2: No valid crystal frequency found in FLASH
(12 MHz RC Oscillator in specified range for
default crystal frequency)
-3: No valid crystal frequency found in FLASH
(12 MHz RC Oscillator out of specified range for
default crystal frequency)
115
ROM Library Functions
(LSByte). If the value found at this
Revision 1.0, 2011-12-15
SP37