4.4 Power On/Off Control
The Tile can be externally switched on/off by an user-supplied load switch on the 3V3 power
rail. After a Tile has been powered off, power should not be restored until at least 1 second has
elapsed. Additionally, if a unit does not respond to software commands, power off the module,
wait for at least 1 second and then power it back on. If the 1 second minimum wait time is not
adhered to, the reset circuit may not operate and the Tile could be placed in a non-operational
state. The state is not permanent and can be rectified by the above procedure.
4.5 Serial Data Interface
The serial data interface is a CMOS serial UART 3-wire (serial Rx, serial Tx, and ground)
interface at 3.3V digital signal levels over which the Tile transfers commands, responses, and
message data. The serial communication parameters can be found in
Table 11
.
Parameter
Value
Baud Rate
115200
Data Bits
8 Bits
Parity
None
Stop bits
1 Bit
Flow Control
None
Table 11:
Serial communication parameters.
In addition, the electrical characteristics for SERIAL_RX, SERIAL_TX, and GPIO1 can be found
in
Table 12.
Symbol
Parameter
Min
Typ
Max
Unit
VIL
I/O input low level voltage
-0.3
-
0.3*VCC V
VIH
I/O input high level voltage
0.7*VCC
-
VCC
V
RPU/RP
D
Weak pull up/down equivalent
resistor (for GPIO1)
25
40
55
kΩ
Table 12:
Electrical characteristics for SERIAL_RX, SERIAL_TX, and GPIO1.
October 2020
Swarm Tile Manual - Rev 1.10
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