Glitch on P1[0] at POR and XRES
Anonymous
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Mar 27, 2011
05:20 PM
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Mar 27, 2011
05:20 PM
Question: After POR or XRES event, P1[0] goes high for some time. Why is it so?
Answer:
All GPIO pins in the PSoC are in the HighZ state during POR or XRES reset events. But Pins P1[1] and P1[0] are ISSP pins and respond differently to a POR or XRES event than other IO pins.
At power up, the internal POR causes P1[0] to initially drive a strong high (1) while P1[1] drives a resistive low (0). After 256 sleep oscillator cycles (approximately 8 ms), the P1[0] signal transitions to a resistive low state. After additional 256 sleep oscillator clocks, both pins transition to a high impedance state and normal CPU operation begins.
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