Microchip Technology RN4870-I/RM128, Manual, Page: 11 / 55

RN4870/71
DS50002489E-page 8 2016-2021 Microchip Technology Inc.
1.2 Module Configuration
The GPIO pins of the RN4870 and RN4871 modules
can be configured for different functions using the
ASCII command interface.
Table 1-3 shows the various
pins in the RN4870/71 module that are available for
configuration and their default configuration settings.
Table 1-4 provides details on each available function.
Table 1-5 shows the status of the module as indicated
by the Status 1 and Status 2 indication pins. Table 1-6
shows the details of test pads that are present on the
bottom side of the module, used for diagnostic
purposes during testing.
Figure 1-5 shows all the key
elements of the module.
TABLE 1-3: CONFIGURABLE PINS AND DEFAULT FUNCTIONS IN THE RN4870 AND RN4871
Pin Name
Available in
Default Function
RN4870 RN4871
P0_7 x Low Battery Indication
P1_0 x Status 2
P1_1 x Status 1
P2_2 x None
P2_4 x None
P3_1 x RSSI Indication
P3_2 x Link Drop
P3_3 x UART RX Indication
P3_4 x Pairing Key
P3_5 x None
P1_2 x x None
P1_3 x x None
P1_6 x UART RX Indication
P1_7 x None
TABLE 1-4: CONFIGURABLE FUNCTIONS AND DESCRIPTIONS
Function Name Description
Low Battery Indication Pin output goes low when the V
DD
is below a specified level. To set the threshold
level, change the EEPROM settings.
Status 1 Use this indication pin along with the Status 2 pin to indicate the current status of
the module. Refer to
Table 1-5 for details of the status indication.
Status 2 Use this indication pin along with the Status 1 pin to indicate the current status of
the module. Refer to
Table 1-5 for details of the status indication.
RSSI Indication Use this indication pin to indicate the quality of the link based on the RSSI level.
If the RSSI level is lower than the specified threshold value, then the RSSI
indication pin goes low. Set the threshold for the RSSI link quality in EEPROM.
Link Drop When the RN4870/71 is connected to a remote device, the host MCU can use
the Link Drop pin to force the module to disconnect the link and enter Shutdown
state. The pin needs to be pulled low for at least 10 ms.
UART RX Indication Use this pin to enable communication with the UART when the module is in Low-
Power mode. When
not in Low-Power mode, the module runs on a 16 MHz
clock. If Low-Power mode is enabled on the module by using the command,
SO,1
, the module runs on a 32 kHz clock, thus reducing power consumption.
However, in Low-Power mode, the host MCU cannot communicate with the
module via the UART since the UART is not operational. If the user intends to
provide data or commands via UART in the Low-Power mode, then the UART
RX Indication pin must be pulled low and the user needs to wait for at least five
milliseconds before sending the data. Pulling the UART RX Indication pin low
allows the module to operate the 16 MHz clock and to enable UART.