Pin Direction And Pullup Control; Table 7 Pin Direction And Pullup Control - Intel Edison Kit for Arduino Hardware Manual

2.6

Pin direction and pullup control

For most shield pins on the Intel® Edison kit for Arduino*, there is a buffer/level-shifter which needs to be
configured for input or output direction, and an external 47 kohm pullup/pulldown resistor, which may be
optionally enabled. Both are driven by dedicated GPIO outputs, listed in Table 7. When configuring a shield pin as
an output, we advise configuring the buffer for output before setting the SoC GPIO pin direction to output. To
disconnect the external pullup/pulldown resistors, it is necessary to configure as high-impedance inputs the GPIOs
that drive them.
Note also that the GPIO signals from the PCAL9555A GPIO expanders have internal 100 kohm pullup resistors,
which are connected to the GPIO pins by default. These need to be disabled in many cases, by configuring those
pins as high-impedance inputs.
Table 7 Pin direction and pullup control
Shield Output enable GPIO (high = output)
pin
Pin
U34_ IO0.0
IO0
U34_ IO0.1
IO1
U34_ IO0.2
IO2
U34_ IO0.3
IO3
U34_ IO0.4
IO4
U34_ IO0.5
IO5
U34_ IO0.6
IO6
U34_ IO0.7
IO7
U34_ IO1.0
IO8
U34_ IO1.1
IO9
U34_ IO1.2
IO10
U34_ IO1.3
IO11
U34_ IO1.4
IO12
U34_ IO1.5
IO13
U16_ IO0.0
IO14
U16_ IO0.1
IO15
U16_ IO0.2
IO16
U16_ IO0.3
IO17
U16_ IO0.4
IO18
U16_ IO0.5
IO19
1 These pins are externally pulled down inputs at power-on. This effectively selects input direction for level shifters.
2 These pins are internally pulled up inputs at power-on. This effectively enables pullups (as 100 kohm + 47 kohm in series).
Intel® Edison Kit for Arduino*
Hardware Guide
12
Linux Power-on default
248 Pulled-down input
249 Pulled-down input
250 Pulled-down input
251 Pulled-down input
252 Pulled-down input
253 Pulled-down input
254 Pulled-down input
255 Pulled-down input
256 Pulled-down input
257 Pulled-down input
258 Pulled-down input
259 Pulled-down input
260 Pulled-down input
261 Pulled-down input
232 Pulled-down input
233 Pulled-down input
234 Pulled-down input
235 Pulled-down input
236 Pulled-down input
237 Pulled-down input
Pullup enable GPIO
1
Pin
U39_IO0.0
U39_IO0.0
U39_IO0.0
U39_IO0.0
U39_IO0.0
U39_IO0.0
U39_IO0.0
U39_IO0.7
U39_IO0.7
U39_IO0.7
U39_IO0.7
U39_IO0.7
U39_IO0.7
U39_IO0.7
U17_ IO1.0
U17_ IO1.1
U17_ IO1.2
U17_ IO1.3
U17_ IO1.4
U17_ IO1.5
§
Document Number: 331191-004
Shield pin configuration
Linux Power-on default
216 Pulled up input
217 Pulled up input
218 Pulled up input
219 Pulled up input
220 Pulled up input
221 Pulled up input
222 Pulled up input
223 Pulled up input
224 Pulled up input
225 Pulled up input
226 Pulled up input
227 Pulled up input
228 Pulled up input
229 Pulled up input
208 Pulled up input
209 Pulled up input
210 Pulled up input
211 Pulled up input
212 Pulled up input
213 Pulled up input
December 2014
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