Timer2 Aux

tick to frequency conversions
Timer ticks to overlow frequency and vice versa convertions
#define	timer2_uint16_ticks_to_freq100(ticks)   (timer_uint16_ticks_to_freq100(ticks, get_timer2_clock_divider(), get_frequency_divider_scale()))
	Convert ticks to timer frequency for timer2 multiplied by 100. More...
#define	timer2_frequency_to_ticks_unsafe(frequency)   (timer_frequency_to_ticks_unsafe(frequency, get_timer2_clock_divider(), get_frequency_divider_scale()))
	Unsafe approximation timer2 frequency corresponding to ticks. More...
#define	timer2_ticks_to_ms_usafe(ticks)   (timer_ticks_to_ms_usafe(ticks, get_timer2_clock_divider(), get_frequency_divider_scale()))
	Convert ticks count to ms. More...

UART baud rate to ticks
UART baud rate to timer ticks to overlow frequency and vice versa convertions
#define	timer2_mode0_baudrate_to_ticks(uart_baudrate)   ((get_master_clock_frequency() >> get_frequency_divider_scale())/4/uart_baudrate)
	Calculate timer2 ticks for UART baudrate. More...
#define	timer2_ms_to_ticks_usafe(ms)   (timer_ms_to_ticks_usafe(ms, get_timer2_clock_divider()))
	Convert milliseconds to timer2 ticks. More...

Detailed Description

Functions and data structures for converting timer ticks to frequency and times for timer2.

Author

Michael Golovanov

Macro Definition Documentation

timer2_frequency_to_ticks_unsafe

#define timer2_frequency_to_ticks_unsafe

(

frequency

)

(timer_frequency_to_ticks_unsafe(frequency, get_timer2_clock_divider(), get_frequency_divider_scale()))

Unsafe approximation timer2 frequency corresponding to ticks.

ticks = get_master_clock_frequency() / (2 * get_timer2_clock_divider() * frequency))

Call this method after timer2 is initialized and MCU clock frequency divider scale is set.

This method doesnt analyze corner cases and overflow of result. Be careful.

Parameters

frequency

uint32_t frequency value in Hz. Should not be 0;

Returns

uint16_t timer0 ticks corresponding to frequency value

timer2_mode0_baudrate_to_ticks

#define timer2_mode0_baudrate_to_ticks

(

uart_baudrate

)

((get_master_clock_frequency() >> get_frequency_divider_scale())/4/uart_baudrate)

Calculate timer2 ticks for UART baudrate.

Adapted for use mcu frequency divider. On some baudrates get not exact values. The reasons are

• Formula not get int values
• Divisions doesnt support floats and accumulate integer division errors

freq/4 = 2764800

Freq div	Baudrate	Ticks hex
1	9600	0x120
1	19200	0x90
1	38400	0x48
1	57600	0x30
1	74880	0x24
1	115200	0x18
1	230400	0x0C
1	250000	0x0B

freq / 8 = 1382400

Freq div	Baudrate	Ticks hex
2	9600	0x90
2	19200	0x48
2	38400	0x24
2	57600	0x18
2	74880	0x12
2	115200	0x0C
2	230400	0x06
2	250000	0x05 0x06?

freq/16 = 691200

Freq div	Baudrate	Ticks hex
4	9600	0x48
4	19200	0x24
4	38400	0x12
4	57600	0x0C
4	74880	0x09
4	115200	0x06
4	230400	0x03
4	250000	0x02-0x03?

Parameters

uart_baudrate

uint16_t UART baudrate

Returns

uint16_t timer2 ticks count for UART baudrate

timer2_ms_to_ticks_usafe

#define timer2_ms_to_ticks_usafe

(

ms

)

(timer_ms_to_ticks_usafe(ms, get_timer2_clock_divider()))

Convert milliseconds to timer2 ticks.

1 ms = ((get_master_clock_frequency_high_part() + 26) >> get_frequency_divider_scale()) / timer_clock_divider

This routine doesnt check overflows. Its unsafe.

Parameters

ms	uint16_t ms to convert

Returns

uint16_t ticks count for milliseconds

timer2_ticks_to_ms_usafe

#define timer2_ticks_to_ms_usafe

(

ticks

)

(timer_ticks_to_ms_usafe(ticks, get_timer2_clock_divider(), get_frequency_divider_scale()))

Convert ticks count to ms.

This method doesnt analyze corner cases and overflow of result. Be careful.

Parameters

ticks

uint16_t ticks count

Returns

milliseconds time corresponing to timer ticks

timer2_uint16_ticks_to_freq100

#define timer2_uint16_ticks_to_freq100

(

ticks

)

(timer_uint16_ticks_to_freq100(ticks, get_timer2_clock_divider(), get_frequency_divider_scale()))

Convert ticks to timer frequency for timer2 multiplied by 100.

The output frequency = (SYSclk/timer_clock_divider)/((65536-ticks) * 2). Multiplication by 100 is used for get frequency value without using float numbers.

Call this method after timer2 is initialized and MCU clock frequency divider scale is set.

Parameters

ticks

uint16_t timer ticks count to covert

Returns

uint32_t frequency multiplied by 100 corresponding to ticks count