libopencm3
A free/libre/opensource firmware library for various ARM CortexM3 microcontrollers.

Macros  
#define  STK_CALIB_NOREF (1 << 31) 
NOREF: NOREF flag Bit31 => NOREF Indicates whether the IMPLEMENTATION DEFINED reference clock is implemented: 0 = The reference clock is implemented. More...  
#define  STK_CALIB_SKEW (1 << 30) 
SKEW: SKEW flag Bit30 => SKEW Indicates whether the 10ms calibration value is exact: 0 = 10ms calibration value is exact. More...  
#define  STK_CALIB_TENMS 0x00FFFFFF 
TENMS Calibration value for 10ms. More...  
#define STK_CALIB_NOREF (1 << 31) 
NOREF: NOREF flag Bit31 => NOREF Indicates whether the IMPLEMENTATION DEFINED reference clock is implemented: 0 = The reference clock is implemented.
1 = The reference clock is not implemented. When this bit is 1, the CLKSOURCE bit of the SYST_CSR register is forced to 1 and cannot be cleared to 0.
#define STK_CALIB_SKEW (1 << 30) 