DSP28335 eCAP module capture pulse problem

闵丨大

DSP28335 eCAP module capture pulse problem [Copy link]

DSP28335 eCAP module capture pulse problem

Hey guys, I want to ask a question. Is the result of the pulse rising edge count captured by the eCAP module of DSP28335 related to the amplitude of the pulse itself?

Today I learned about the eCAP module and burned the sample code to the development board. I used the function signal generator to generate a square wave with a frequency of 10KHz, Vpp=1V and a duty cycle of 0.5. I observed the T1 value through the watchwindow and found that T1 fluctuated around 2200. Then I changed the square wave amplitude to Vpp=3.0V and found that the T1 value was close to 15000. The screenshot is as follows.

T1=150MHz/10KHz。

TMS320F28335 operating frequency = 150MHz

Measured signal frequency = 10KHz

Figure 1: Vpp=1V Figure 2: Vpp=3V

Figure 1 Vpp=1V

Figure 2 Vpp=3V

littleshrimp

The digital signal voltage cannot be too low. Please refer to the data sheet for details.

闵丨大

littleshrimp posted on 2019-7-31 20:16 The voltage of the digital signal cannot be too low. Please refer to the data sheet for details

Thank you for your reply. I have roughly understood it and will look at the eCAP data sheet later.

littleshrimp

Min丨Da published on 2019-7-31 21:44 Thanks for your reply. I roughly understand it. I will look at the eCAP data sheet later.

Voltage is basically the electrical characteristics of the digital IO part