I am connecting a sensor that has a 3.3V output to an STR7 TTL input (via a breadboard). If I disconnect the sensor from the breadboard, I see that its output level swing to 3.3V and falls to 0V as expected. But the STR7 input, if connected to the sensor, only allows the sensor voltage to rise to about half the need value - 1.56V. The input is configured like this:
GPIO_Config(GPIO0, 0x0001 << 0x0F, GPIO_IN_TRI_TTL);
There are exotic things in between. What am I missing?
Thanks
The CMOS input does not clamp the voltage, but the sensor never exceeds 3V3. Well, as long as it is clamped by P0.15 I cannot use it (not a big deal to be honest) because the microcontroller never detects 1.56V as "logic 1" (input is used as a wake-up from low power mode...). I will try to set P0.15 to input mode at the beginning of "main()" and see what voltage levels are reached. Maybe it is something in the software, after all.