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TOBY-R2 series - System integration manual
UBX-16010572 - R10
Design-in
Page 116 of 151
2.8
General Purpose Input/Output
2.8.1.1
Guidelines for GPIO circuit design
A typical usage of TOBY-R2 series modules’ GPIOs can be the following:
Network indication provided over GPIO1 pin (see
GNSS supply enable function provided by the GPIO2 pin (see section
GNSS Tx data ready function provided by the GPIO3 pin (see section
GNSS RTC sharing function provided by the GPIO4 pin (see section
SIM card detection provided over GPIO5 pin (see
TOBY-R2 series
GPIO1
R1
R3
3V8
Network Indicator
R2
21
DL1
T1
Figure 65: Application circuit for network indication provided over GPIO1
Reference
Description
Part Number - Manufacturer
R1
10 k
Resistor 0402 5% 0.1 W
Various manufacturers
R2
47 k
Resistor 0402 5% 0.1 W
Various manufacturers
R3
820
Resistor 0402 5% 0.1 W
Various manufacturers
DL1
LED Red SMT 0603
LTST-C190KRKT - Lite-on Technology Corporation
T1
NPN BJT Transistor
BC847 - Infineon
Table 49: Components for network indication application circuit
☞
Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 k
resistor
on the board in series to the GPIO of TOBY-R2 series modules.
☞
Do not apply voltage to any GPIO of the module before the switch-on of the GPIOs supply (V_INT),
to avoid latch-up of circuits and allow a proper module boot. If the external signals connected to
the module cannot be tri-stated or set low, insert a multi channel digital switch (e.g. TI
SN74CB3Q16244, TS5A3159, TS5A63157) between the two-circuit connections and set to high
impedance before V_INT switch-on.
☞
ESD sensitivity rating of the GPIO pins is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level could be required if the lines are externally accessible and it can be achieved
by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible
points.
☞
If the GPIO pins are not used, they can be left unconnected on the application board.
2.8.1.2
Guidelines for general purpose input/output layout design
The general purpose inputs / outputs pins are generally not critical for layout.