TWR-RF-SNAP User’s Manual
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I2C (SNAP I2C):
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Connected to Physical Pins 28-29 – SNAP GPIO 13-12
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SCL = Pin_29/GPIO_12, SDA = Pin_28/GPIO_13
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This interface port attaches to edge-connectors (elevator) for communication with other
devices within the Tower System as well as the on-board TWRPI socket
SPI (SNAP SPI):
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Connected to Physical Pins 35, 39-41 – SNAP GPIO 7-4
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SCK = Pin_35/GPIO_7, MOSI = Pin_39/GPIO_6, MISO = Pin_40/GPIO_5, SS = Pin_41/GPIO_4
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This serial interface bus attaches to edge-connectors (elevator) for communication with other
devices within the Tower System
ADC:
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ADC1 has the capability to use an on-board 2.5V precision voltage reference
GPIO Expansion Header:
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The GPIO header exposes the following pins for use external to the TWR-RF-SNAP board:
GPIO Header (J6)
Pin Description
1
SNAP GPIO_28 / Keyboard Interrupt 6 (KBI_6)
2
Vcc (3.3V)
3
SNAP GPIO_29 / Keyboard Interrupt 7 (KBI_7)
4
SNAP GPIO_0 / SSI_TX
5
SNAP GPIO_1 / SSI_RX
6
SNAP GPIO_2 / SSI_FSYN
7
SNAP GPIO_3 / SSI_BITCK
8
SNAP GPIO_21 / UART1_RTS (SNAP SW UART0)
9
GND
10
SNAP GPIO_20 / UART1_CTS (SNAP SW UART0)