ISM480 GPS State of Pins after Reset

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After a reset (internally pulled up, power up generates the first reset) and before the first time ON_OFF.

Pin      Description      Reset State

1        CTS/SPI_CL/GPIO6      Pad Enabled, Low, Weak Pull-down Enabled

2        RX/MOSI/SDA          Pad Enabled, High

3        TX/MISO/SCL            Pad Enabled, High

4        RTS/SPI_CS/GPIO7        Pad Enabled, High, Weak Pull-up Enabled

5        Reset                   Pad Enabled, High, Pull-up Enabled

6        Wakeup                 Pad Enabled, Low

7        On_OFF                 Pad Enabled, Low

8        Flash Enable            Pad Enabled, Low

9        GPIO3                     Pad Enabled, High

When  the ON_OFF is pulsed for the first time the levels of  GPIO6 and GPIO7 are read to configure the host interface.

The reset is looked at by SiRF/CSR as an “External emergency override of internal POR”, so it is recommend to control the GPS through the use of the ON_OFF pin