| Apollo Register Documentation v2.2.0

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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.