Application Note: MM002 Hardware Overview

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Purpose of this Application Note is to help engineer to integrate MM002 Hardware. This Application Note is valid for all MM002-xx-EU Modules.


1 Pins assignment

PAD number Function Comment
1 GND
2 /NRST Reset of module. Active at low level. Put a 100nF on this pin.
3 I2C_SDA / GPIO I2C bus
4 I2C_SCL / GPIO I2C bus
5 NC
6 USART1_RX / GPIO USART1
7 USART1_TX / GPIO USART1
8 NJTRST / GPIO JTAG Reset
9 JTDO / GPIO JTAG Data Output
10 JTDI / GPIO JTAG Data Input
11 JTCK-SWCLK / GPIO JTAG Clock
12 JTMS-SWDAT / GPIO JTAG Mode Select
13 GPIO
14 GPIO
15 GND
16 GND
17 ANT RF antenna port matched to 50Ω. No DC capacitor required
18 GND
19 SPI_MOSI SPI bus
20 SPI_SCK SPI bus
21 SPI_MISO SPI bus
22 SPI_NSS SPI bus
23 USART2_RX / ADC / GPIO
24 USART2_TX / ADC / GPIO
25 USART2_CTS / WAKEUP1 / ADC / GPIO
26 USART2_RTS / ADC / GPIO
27 VCC 3V supply of the board
28 GND

2 Application circuit

2.1 Using with companion MCU chipset

When the module is planned to be controlled with external microcontroller chipset, then the UART connection will be used.

The mandatory module pins to connect to external companion MCU are:

  • UART_TX : module pin 24
  • UART_RX: module pin 23
  • Wake up: module pin 25

Optional pin to connect to companion MCU is RESET (module pin 2). Reset is active at low level.

It is recommended to add a 100nF capacitor on Reset pin: this will avoid any untimely reset of the product due to ESD discharges.

The others I/O pins can be left not connected.

2.2 Power supply

To supply the module, connect to VCC pin 27.

Recommended 
3V level with a minimum of 2.7V and maximum of 3.3V.

Internal decoupling capacitors on power supply line inside the module are already placed with capacitors values of 4.7µF and 100nF.

No need to add external decoupling capacitor on VCC pin 27.

We recommend to place a ferrite bead on VCC line: recommended reference is MPZ1608D101B from TDK.

Impact of power supply level on TX power

The TX power is sensitive to external power level on Vcc.

Measure of TX power level depending of voltage level, and current consumption associated:

   VCC=3.3V: Measure of Tx power on antenna pin=14.2dBm, I=43.5mA
   VCC=3V: Measure of Tx power on antenna pin=13.65dBm, I=40.1mA
   VCC=2.7V: Measure of Tx power on antenna pin=12.85dBm, I=36.6mA
   VCC=2.4V: Measure of Tx power on antenna pin=11.83dBm, I=32.3mA (absolute low voltage level)
   VCC=1.8V: Measure of Tx power on antenna pin=7.73dBm, I=24.5mA (not recommended)

2.3 Antenna connection

On antenna RF pin 17, we recommend to place a pi matching network in order to match the impedance presented by the antenna connected to the board and the impedance presented by module antenna output.

The module antenna output is already matched to 50ohms in the frequency region band chosen.

ESD protection can be added to antenna port if the antenna is external to the product case. We recommend to use ESD8472MUT5G from On Semiconductor.

3 Module PCB

3.1 MM002 module dimensions

MM002 dimensions.png

3.2 Layout footprint for MM002 module integration

MM002 footprint.png

4 Reference schematic

4.1 BOM of the reference

  • TPS78101DDCR from Texas Instrument
  • ESD8472MUT5G from On Semiconductors
  • ESHF-105-01-L-D-SM from SAMTEC
  • UFL connector: U.FL-R-SMT-1(10) from Hirose
  • Battery connector: 62000211722 from Wurth Elektronik

4.2 Schematic

Schéma lora.JPG Power supply.JPG

In option:

Debug connection.JPG

4.3 Layout

Top view.JPG

Bottom view MM002.JPG