gpio output voltage

[William.wei]

hi support team,

may i ask how to understand below two items in our 833 sepc? customer is worring about our gpio drive capability:

for question1, why gpio output high voltage would be vdd-0.4? is it because of drive capability? even using high drive mode the output would be still vdd-0.4.

for quesiton2, "10mA for output low and 9mA for output high" is just for one gpio pin, right? may i ask the total gpio output current? in other words howmany pins can be set to H0H1? or S0H1?

qustion3, high drive low current is at 6 to 15mA, why there is one item that high drive 5mA or high drive 3mA? can we setting gpio drive to high drive at 5mA or 3mA?

regards,

William.

[ketiljo]

for question1, why gpio output high voltage would be vdd-0.4? is it because of drive capability? even using high drive mode the output would be still vdd-0.4.

The outpout voltage is < VDD - 0.4 V at the stated current. If the current deliveres is higher, the voltage will be lower. Think of it as an internal series resistor. 

for quesiton2, "10mA for output low and 9mA for output high" is just for one gpio pin, right? may i ask the total gpio output current? in other words howmany pins can be set to H0H1? or S0H1?

Yes, one GPIO. This is how current you can draw before the voltage drops with 0.4 V

You can have 3 GPIOs at full current. 

qustion3, high drive low current is at 6 to 15mA, why there is one item that high drive 5mA or high drive 3mA? can we setting gpio drive to high drive at 5mA or 3mA?

Different supply voltage. In this case, the output is low and you can for instance draw at least 5 mA before the voltage is lifted with at VDD > 2.7 V