AN3070

Measuring the DE signal switching time using the two methods

Doc ID 16312 Rev 1

9/12

3.1.1

Measuring the DE signal switching time using the DMA interrupt

method

Table 1 gives the different timings measured at 72 MHz using the DMA interrupt method.

Table 2 gives the different timings measured at 24 MHz using the DMA interrupt method.

3.1.2

Measuring the DE signal switching time using the USART interrupt

method

Table 3 gives the different timings measured at 72 MHz using the USART interrupt method.

Table 4 gives the different timings measured at 24 MHz using the USART interrupt method.

Table 1.

Timing measurements of DE switching at 72 MHz

Compiler

Number of CPU cycles

IAR 5.40 / Keil 4.0

about 25

Table 2.

Timing measurements of DE switching at 24 MHz

Compiler

Number of CPU cycles

IAR 5.40 / Keil 4.0

about 22

Table 3.

Timing measurements of DE switching at 72 MHz

Compiler

Number of CPU cycles

IAR 5.40 / Keil 4.0

about 43

Table 4.

Timing measurements of DE switching at 24 MHz

Compiler

Number of CPU cycles

IAR 5.40 / Keil 4.0

about 33