Datasheet

FS98O22

Rev. 1.6 79/146

7.3. Digital I/O Port or PDM Output : PT2[2] and PT2[5]

Figure 7-3 PT2[2] function block

GPIO Port 2 Bit2 (PT2[2]) and GPIO Port 2 Bit5 (PT2[5]) function block is shown in Figure 7-3. The main

function of the GPIO is input and output data between the Data bus and the ports. User could control the

PT2EN[2]/ PT2EN[5] register flags to decide the input output direction. The input and output function and the

related functions are explained as follows:

z Input:

GPIO Port 2 Bit2 (PT1[2]) and GPIO Port 2 Bit5 (PT1[5]) could be the PDM (Pulse Density Modulator)

output port or be the general I/O port. User should setup PM1EN/ PM2EN register flag to decide if the

PDM is enabled. The detailed PDM usage is described in Chapter 8.

The input port has a Schmitt trigger in it, and the up/down trigger voltage level is 0.45VDD/0.2VDD.

z Output

FS98O22 sends the digital data out by an embedded D Flip Flop. When the program sends data out

through PT2, the data will be sent to data bus first, and then the D Flip Flop will latch the signal for PT2

output while the Write signal and AR (FS98O22 internal device address pointer) is pointed to PT2.

z Pull up resistor

FS98O22 embeds an internal pull up resistor function in PT2 with about 1000k ohm resistor

. Users

could control the PT2PU[2]/PT2PU[5] register flags to decide the connection to pull up resistor. When a

port is connected to the pull up resistor, the input data is, by default, assigned to high (data 1).

The pull up current is about 10uA. Remember to disable PT1PU before program falls into Sleep mode.

FORTUNE'

Properties

For Reference Only