UM0282
STR9 Dongle
1.8
Assembling instructions for lite version
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CAN transceiver U9 – not assembled
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Connectors CN3, CN4, CN5, CN9 – not assembled
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Crystal X2 – use this one GM: 131-082 (Q32.768KHZM)
1.9 Application
hints
1.9.1 Ethernet
interface
Clock input
The clock is provided directly by the STR912FAWxx device. It is mandatory to enable this
feature on pin P52 before starting.
Address inputs
The DMA address is fixed and set to 0x10. It is defined by configuring resistors R711, R712,
R713, R715, and R717.
Reset
The reset input is connected to STR912FAWxx Reset-out pin.
Power-down
The STR912FAWxx can be quickly put in Power-down mode by using the P01 pin. After a
Reset, P01 is configured as an input and R719 acts as a pull-down resistor, thus making the
PHY active by default. To put the PHY into Power-down mode, P01 must be configured as a
push-pull output and held High.
1.9.2 USB
interface
Disconnect on demand
The pull-up resistor R67 is driven by P75 pin. It tells the host whether the device is
connected or not. After a Reset, P75 is configured as an input, which means that T2 is open
and T1 closed. R67 consequently does not act as a pull-up resistor thus making the device
disconnected by default. It is mandatory to configure pin P75 as an output (open-collector)
and hold it Low before starting using the USB interface.
