Digi NS9210 - Manual (Page 34)

34 NS9210 Processor Module Hardware Reference
C h a p t e r 1
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Master: 33.33 Mbps
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Slave: 7.50 Mbps
The SPI module is made of four signals: RXD, TXD, CLK and CS#
I
2
C bus
The I 2 C bus is completely free on the module - no EEPROM and no RTC - since the RTC
is in the processor.
The I²C clock is max 400kHz.
I2C signals are provided on the module with 4k7 pull-up resistors.
RTC
The RTC is integrated in the processor and has its own 32.768 KHz clock crystal.
„
When powered by VBAT, RTC unit will function until VBAT (X1.78) reaches a
threshold of 2.3 - 2.4V - then the internal unit switches off.
„
The battery current without +3.3V power applied is up to 40µA. The current is
used to power the RTC, 32.768kHz oscillator and 64-byte internal RAM.
„
When the development board ships from the factory the battery is disabled. To
enable the battery, place a jumper on the development board at J2.
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P o w e r
Power supply
The module has +3.3V and VLIO supply pins.
VLIO can be connected either to a Li-Ion battery (2.5V - 5.5V) in a mobile application,
or it can be connected directly to +3.3V. Connecting VLIO to a battery causes
efficiency to be gained without an additional voltage regulator.
Internal voltage
The internal 1.8V core voltage is generated through a high-efficiency synchronous
step-down converter, which uses VLIO as input voltage. The core voltage regulator
can provide up to 600mA.