Apollo Register Documentation  v${version}
SYSTICK - ARM System Timer (SysTick) Block Registers.

SYSTICK Register Index

  0xE000E010:   SYSTCSR - SysTick Control and Status Register.
  0xE000E014:   SYSTRVR - SysTick Reload Value Register.
  0xE000E018:   SYSTCVR - SysTick Current Value Register.
  0xE000E01C:   SYSTCALIB - SysTick Calibration Value Register.

SYSTCSR - SysTick Control and Status Register.

Address:

  Instance 0 Address:   0xE000E010

Description:

SysTick Control and Status Register.

Example Macro Usage:

//
// All macro-based register writes follow the same basic format. For
// single-instance modules, you may use the simpler AM_REG macro. For
// multi-instance macros, you will need to specify the instance number using
// the AM_REGn macro format.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
// AM_REGn(<MODULE>, <INSTANCE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
//
// For registers that do not have specific enumeration values, you may use this alternate format instead.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>(<NUMBER>);
//
// For example, the following three lines of code are equivalent methods of
// writing the value for 12MHZ to the CLKSEL field in the ADC_CFG register.
//
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REGn(ADC, 0, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL(0x1);

Register Fields:

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD
0x0
COUNTFLAG
0x0
RSVD
0x0
TICKINT
0x0
ENABLE
0x0

Bits Name RW Description
31:17 RSVD RO RESERVED.

16 COUNTFLAG RO Returns 1 if timer counted to 0 since last time this was read.

15:2 RSVD RO RESERVED.

1 TICKINT RW Enables SysTick exception request. Software can use COUNTFLAG to determine if SysTick has ever counted to zero. 0 = counting down to zero does not assert the SysTick exception request; 1 = counting down to zero asserts the SysTick exception request.

0 ENABLE RW Enables the counter. 0 = counter disabled; 1 = counter enabled.


SYSTRVR - SysTick Reload Value Register.

Address:

  Instance 0 Address:   0xE000E014

Description:

SysTick Reload Value Register.

Example Macro Usage:

//
// All macro-based register writes follow the same basic format. For
// single-instance modules, you may use the simpler AM_REG macro. For
// multi-instance macros, you will need to specify the instance number using
// the AM_REGn macro format.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
// AM_REGn(<MODULE>, <INSTANCE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
//
// For registers that do not have specific enumeration values, you may use this alternate format instead.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>(<NUMBER>);
//
// For example, the following three lines of code are equivalent methods of
// writing the value for 12MHZ to the CLKSEL field in the ADC_CFG register.
//
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REGn(ADC, 0, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL(0x1);

Register Fields:

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD
0x0
RELOAD
0x0

Bits Name RW Description
31:24 RSVD RO RESERVED.

23:0 RELOAD RW Value to load into the SYSTCVR register when the counter is enabled and when it reaches 0.


SYSTCVR - SysTick Current Value Register.

Address:

  Instance 0 Address:   0xE000E018

Description:

SysTick Current Value Register.

Example Macro Usage:

//
// All macro-based register writes follow the same basic format. For
// single-instance modules, you may use the simpler AM_REG macro. For
// multi-instance macros, you will need to specify the instance number using
// the AM_REGn macro format.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
// AM_REGn(<MODULE>, <INSTANCE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
//
// For registers that do not have specific enumeration values, you may use this alternate format instead.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>(<NUMBER>);
//
// For example, the following three lines of code are equivalent methods of
// writing the value for 12MHZ to the CLKSEL field in the ADC_CFG register.
//
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REGn(ADC, 0, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL(0x1);

Register Fields:

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD
0x0
CURRENT
0x0

Bits Name RW Description
31:24 RSVD RO RESERVED.

23:0 CURRENT RW Reads return the current value of the SysTick counter. A write of any value clears the field to 0, and also clears the SYSTCSR COUNTFLAG bit to 0.


SYSTCALIB - SysTick Calibration Value Register.

Address:

  Instance 0 Address:   0xE000E01C

Description:

SysTick Calibration Value Register.

Example Macro Usage:

//
// All macro-based register writes follow the same basic format. For
// single-instance modules, you may use the simpler AM_REG macro. For
// multi-instance macros, you will need to specify the instance number using
// the AM_REGn macro format.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
// AM_REGn(<MODULE>, <INSTANCE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>_<VALUE>;
//
// For registers that do not have specific enumeration values, you may use this alternate format instead.
//
// AM_REG(<MODULE>, <REGISTER>) |= AM_REG_<MODULE>_<REGISTER>_<FIELD>(<NUMBER>);
//
// For example, the following three lines of code are equivalent methods of
// writing the value for 12MHZ to the CLKSEL field in the ADC_CFG register.
//
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REGn(ADC, 0, CFG) |= AM_REG_ADC_CFG_CLKSEL_12MHZ;
AM_REG(ADC, CFG) |= AM_REG_ADC_CFG_CLKSEL(0x1);

Register Fields:

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
NOREF
0x0
SKEW
0x0
RSVD
0x0
TENMS
0x0

Bits Name RW Description
31 NOREF RO Indicates whether the device provides a reference clock to the processor. 0 = reference clock provided; 1 = no reference clock provided. If your device does not provide a reference clock, the SYST_CSR.CLKSOURCE bit reads-as-one and ignores writes.

30 SKEW RO Indicates whether the TENMS value is exact. 0 = TENMS value is exact; 1 = TENMS value is inexact, or not given. An inexact TENMS value can affect the suitability of SysTick as a software real time clock.

29:24 RSVD RO RESERVED.

23:0 TENMS RW Reload value for 10ms (100Hz) timing, subject to system clock skew errors. If the value reads as zero, the calibration value is not known.