User's Manual

LoRa/BLE Modules
Hardware Integration Guide
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lowers the AIN voltage. However, when the capacitor is connected it should keep the AIN voltage at
previous level for an adequate time period while sampling, minimizing the effect of the high
resistance value of the external voltage divider. The capacitor should be big enough to hold voltage
up for the required time period, i.e. 20 us for 8 bit sampling or 68 us for 10 bit sampling. If you use a
FET transistor to open the current flow through the circuit momentarily before sampling, allow
enough time for the capacitor to fully charge before sampling. During the sampling period, multiple
samples are made and the ADC output value is the mean value from the sample pool. The sample
pool is created during 20 us period for 8 bit sampling, 36 us period for 9 bit sampling, and 68 bit
period for 10 bit sampling.
 Two-Wire SWD Programming/Debug Interface
Required if Flash Cloning will be used during production to load RM1xx smartBASIC application and/or
the firmware, add 2-Wire SWD Programming/Debug Interface as detailed in section 2-Wire SWD
Programming/Debug Interface
 UART
Required for loading customer smartBASIC application and firmware. Add connector to allow UART to
be interfaced to PC (via UART –RS232 or UART- USB).
 UART_RX and UART_CTS
SIO_22 (alternative function UART_RX) is an input, set with internal weak pull-up (in FW). The pull-up
prevents the module from going into deep sleep when UART_RX line is idling.
SIO_24 (alternative function UART_CTS) is an input, set with internal weak pull-down (in FW). This pull-
down ensures the default state of the UART_CTS will be asserted which means can send data out of the
UART_TX line. In the case when UART_CTS is not connected (which we do not recommend).
 nAutoRUN pin and operating mode selection
nAutoRUN pin needs to be externally held high or low to select between the two RM1xx operating
modes at power-up:
– Self-contained Run mode (nAutoRUN pin held at 0V).
– Interactive/development mode (nAutoRUN pin held at VCC).
 Make provision to allow operation in the required mode. Add jumper to allow nAutoRUN pin to be held
high or low (via 10K resistor) OR driven by host GPIO.
 I2C
It is essential to remember that pull-up resistors on both I2C_SCL and I2C_SDA lines are not provided in
the RM1xx module and MUST be provided external to the module as per I2C standard.
 SPI
Implement SPI chip select using any unused SIO pin within your smartBASIC application script then
SPI_CS is controlled from smartBASIC application allowing multi-dropping.
 SIO pin direction
RM1xx modules shipped from production with smart BASIC runtime engine FW, all SIO pins (with
“default function” of “DIO”) are mostly digital inputs (see Pin Definitions Table2). Use your smart BASIC
application script to change the direction of any SIO pin that is required to be an output in your design.
Also these SIO pins that are inputs have by default (in FW) an internal pull-up or pull-down resistor-
enabled (see Pin Definitions Table2). This was done to avoid floating inputs (which can also cause
current consumption in low power modes (e.g. StandbyDoze) to drift with time. In any case customer
can disable the PULL-UP through their smart BASIC application.
 nRESET pin (active low)
Hardware reset. Wire out to push button or drive by host.
By default module is out of reset when power applied to VCC pin.