Gpio Pin Special Roles; Table 30.3. Gpio Special Roles - Silicon Laboratories Si4010-C2 Manual

30.1. GPIO Pin Special Roles

Not all GPIO ports can be configured as both input and outputs. Given the limited number of GPIO each
pin can assume different functionality based on the software configuration of the ports. The functionality of
each GPIO is described in Table 30.3.
GPIO Number Other Special Roles
0
1
2
3
4
5
6 (14 pin only)
7 (14 pin only)
8 (14 pin only)
9 (14 pin only)
Notes:
1. Can be set as GPIO input only. Special roles are crystal oscillator (XO) and VPP=6.5V NVM
programming voltage supply during NVM programming.
2. Reference clock source for frequency counter.
3. Current mode driver for LED connected directly to VCC supply. GPIO[5] cannot be used for any
other purpose in user application.
4. Optional customer clock clk_out output can be set independently on GPIO[4] and GPIO[6], or on
both at the same time.
It is important to emphasize the following:
GPIO[0] can be used only as input for user application. It can also serve as a crystal oscillator input.

During device NVM programming the programming VPP=6.5V voltage is applied to this pin.
GPIO[5] can be used only as a up to 1mA LED current driver. The LED should be connected directly in

between the GPIO[5] and VCC. In a development system this pin is used as a C2 interface C2CLK. In
the development system the LED has to be isolated from the pin as shown in Figure 35.1 and
Figure 35.2. The LED is disabled during debugging.

Table 30.3. GPIO Special Roles

C2
1
XO/VPP1
2
clk_ref
clk_out out C2DAT
C2CLK
4
clk_out out
Rev. 1.0
Si4010-C2
FOB Can Drive
Low During
Sleep
button
button Y
button Y
button Y
button
3
LED
button
button
button
button
Pullup Roff
Option
Y
Y
111