STM32 NUCLEO L4R5ZI – STM32 Ultra Low Power Evaluation Board

This blog provides crisp information about STM32 NUCLEO L4R5ZI evaluation board.  This is based on  STM32L4R5ZI  MCU .

This  MCU is most suitable for various wearable applications where very low power is required. The  energy saving strength lies in its architecture and various power saving modes.  It can go as low as 33nA in shutdown mode  and  125nA in standby mode ,  with five wake-up pins.  Even standby mode with RTC takes only  420nA .  The eval board under discussion in this blog has a provision to check current using Ammeter. You need to remove JP5(IDD) and put Ammeter there.

STM32L4R5ZI  Decoding 

  • STM32 -> ARM based 32-bit Microconroller (Cortex®-M4)
  • L -> Ultra Low Power
  • 4R5 ->   Device sub-family STM32L4R5xx
    • 4R7 = STM32L4R7xx, LCD-TFT, Chrom-GRC™
    • 4R9 = STM32L4R9xx, LCD-TFT Chrom-GRC™ and DSI Host
  • Z  -> 144 pins
  • I   -> 2Mbyte Flash Memory.
    • G -> 1Mbyte Flash Memory

Complete part number will have packaging and temperature range information as well.  Please refer to “Ordering Information” in the STM32L4R5ZI datasheet given in reference section.

This is the Getting started for a low cost evaluation platform named Nucleo-L4R5ZI . This board has two parts. Please note the features supported in this board based on MCU part number decoding given above.


It is  the ST-LINK/V2-1 programming and debugging tool . This board also has one ST mcu for supporting debugging capability. By default, It can be used to debug or program the main STM32L4R%ZI MCU  in other part of the board. This ST-Link part can be separated by cutting but in that case main board has to be  configured for other external supply option.

It uses SWD (Serial Wire Debug)

Serial Wire Debug (SWD) is an alternative 2-pin electrical interface that uses the same  JTAG protocol. It uses the existing GND connection and SWDIO , SWCLK signals . SWD uses an ARM CPU standard bi-directional wire protocol, defined in the ARM Debug Interface v5. This enables the debugger to become another  AMBA bus master for access to system memory and peripheral or debug registers.

  • Both CN4 jumpers ON(default)  –  ST-LINK/V2-1 functions enabled for on-board programming.
  • Both CN4 jumpers OFF –  ST-LINK/V2-1 can be used to program any external board with SWD  connector(CN5) .

MCU Part

Power supply options

Following are the various options available  based on jumper JP6 . MCU part has two voltage regulators for converting voltage from VIN to 5V and 5V to 3.3V .  The green LED (LD6 PWR) indicates that the STM32 part is powered and +5 V power is available. The main MCU will use 3.3V.

  • ST-LINK USB power(default)  – The USB connector on ST-LINK part can be connected to PC which will have driver supporting ST-LINK
  • USB charger – The USB connector on ST-LINK part  can be connected to external USB charger.
  • External
    • 3,3V
    • 5 V  at  E5V
    • 7V-12V at VIN

Zio Connectors 

  • CN7 – PWM, SPI, I2S(Integrated Inter-IC Sound Bus) etc
  • CN8  – SDMMC, VIN,NRST etc
  • CN9 – USART, I2C, CAN, SAI( Serial Audio Interface) etc
  • CN10 – Timer, PWM, QSPI, ADC etc

Note:  The connectors CN7, CN8, CN9 and CN10 include support for Arduino Uno shield.

Morpho connectors

All signals and power pins of the STM32 are available on the ST morpho connectors :

  • CN11
  • CN12

These connectors can be used to connect the STM32 Nucleo-144 board to an extension board. These un-soldered(default) pin points can be used as test points as well.

Arduino UNO R3 Support 

One has to be cautious here  because the I/Os of the STM32 microcontroller are 3.3 V compatible, while Arduino Uno V3 is 5 V compatible.

USB with Micro-AB





STM32L4R5ZI Datasheet

STM32Nucleo Boards

ST32 Nucleo-L4R5ZI Eval Board Documentation

Purchase option : 

STM32 Nucleo-L4R5ZI Eval Board

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