SysTick timer control
| TENMS | Specifies the number of clock source cycles (minus 1) that make up 10 ms. E.g., for a 32,768 Hz reference clock, TENMS is 328 - 1 = 327. |
| CLOCK_SOURCE | Specifies an external clock source: ‘0’: The low frequency clock ‘clk_lf’ is selected. The precision of this clock depends on whether the low frequency clock source is a SRSS internal RC oscillator (imprecise) or a device external crystal oscillator (precise). ‘1’: The internal main oscillator (IMO) clock ‘clk_imo’ is selected. The MXS40 platform uses a fixed frequency IMO clock. o ‘2’: The external crystal oscillator (ECO) clock ‘clk_eco’ is selected. ‘3’: The SRSS ‘clk_timer’ is selected (‘clk_timer’ is a divided/gated version of ‘clk_hf’ or ‘clk_imo’). Note: If NOREF is ‘1’, the CLOCK_SOURCE value is NOT used. Note: It is SW’s responsibility to provide the correct NOREF, SKEW and TENMS field values for the selected clock source. |
| SKEW | Specifies the precision of the clock source and if the TENMS field represents exactly 10 ms (clock source frequency is a multiple of 100 Hz). This affects the suitability of the SysTick timer as a SW real-time clock: ‘0’: Precise. ‘1’: Imprecise. |
| NOREF | Specifies if an external clock source is provided: ‘0’: An external clock source is provided. ‘1’: An external clock source is NOT provided and only the CPU internal clock can be used as SysTick timer clock source. |