fx2delay.h

The fx2delay.h header contains delay routines for the Cypress FX2 series. When using this header, the fx2 library must be linked in.

Reference

Defines

SYNCDELAYLEN

Synchronization delay length.

This value defaults to 3, and should be overridden using a compiler flag -DSYNCDELAYLEN=n if running with non-default IFCLK or CLKOUT clock frequency. Delay length can be calculated using the following Python code:

import math
math.ceil(1.5 * ((ifclk_period / clkout_period) + 1))

See TRM 15.15 for details.

Functions

void delay_ms(uint16_t count_ms)

Spin for the given number of milliseconds.

void delay_us_overhead(uint16_t count_us, uint8_t overh_c)

Spin for the given number of microseconds, minus overh_c processor cycles. count_us must be no greater than 21845, and overh_c must be no greater than 128.

This function is cycle-accurate at any CPU clock frequency provided that the delay is not less than the intrinsic overhead of up to 100 processor cycles (9..33 microseconds).

void delay_us(uint16_t count_us)

Equivalent to delay_us_overhead(count_us, 3) where 3 is the number of cycles of overhead when delay_us is called with a constant argument.

void delay_4c(uint16_t count_4c)

Spin for count * 4 processor cycles, or count * 16 clock cycles. Takes exactly 24 processor cycles (2..8 microseconds) if count is less than 6.