Hi
I am using a PIC16F1939 processor. I am using a I/O line as an input to detect a high to low transition then to generate an interrupt on PORTB.
I am operating the PIC at 3V. Using a TTL buffer, I see the following information.
Looking at the datasheet VIL is 0.15VDD and the conditions are 1.8V<VDD<4.5V
The Input High VIH is 0.25VDD + 0.8V.
I am not using Schmitt trigger buffer. So am I correct in saying that
VIL
0.15 x VDD = 0.15 x 3V = 0.45V
VIH
0.25 x 3V + 0.8 = 1.55V
So my edge trigger going from high to low will have to be >=1.55V (high) to <=0.45V to be recognised by the PIC as a high to low transition?
Is there anything wrong with my calculations?
Thanks in advance
Raj
I am using a PIC16F1939 processor. I am using a I/O line as an input to detect a high to low transition then to generate an interrupt on PORTB.
I am operating the PIC at 3V. Using a TTL buffer, I see the following information.
Looking at the datasheet VIL is 0.15VDD and the conditions are 1.8V<VDD<4.5V
The Input High VIH is 0.25VDD + 0.8V.
I am not using Schmitt trigger buffer. So am I correct in saying that
VIL
0.15 x VDD = 0.15 x 3V = 0.45V
VIH
0.25 x 3V + 0.8 = 1.55V
So my edge trigger going from high to low will have to be >=1.55V (high) to <=0.45V to be recognised by the PIC as a high to low transition?
Is there anything wrong with my calculations?
Thanks in advance
Raj