AN4635 datasheet(31/34 Pages) STMICROELECTRONICS

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AN4635

Example project

A firmware example is supplied to demonstrate the use of different configurations

mentioned in this document. Most configurations are switchable using the defines section in

the main.c source file.

Two boards are necessary to replicate the measurements referenced in the documentation

as a primary board and a repeater. The repeater must be loaded with DMA FW built with

BOARD2 option.

Measurements of consumption are supposed to be done on the primary board, not on the

repeater.

The example has been developed and tested with STM32L053R8 Nucleo boards.

7.1

HW setup

Just cross connect Tx pins with Rx pins using two wires. JP6 pins can be used to monitor

the power consumption.

7.2

Configuring the example

Various features and working modes of the example FW can be configured using following

preprocessor defines:

DEBUG_OFF – Disables the SWD debug capability on port A and error checking

BOARD2 – Configures the SW as the repeater board (only present in DMA version)

UI – Enables user interface – it is impossible to take correct power consumption readings

with buttons and LEDs enabled

BD_SPEED – Setting of communication baud speed

REG_LP – Attempts to switch to the low power regulator (Polling version only)

PWR_CR_VOS_CONF – Configuration of the main power regulator (range 3 is the default)

TXSLEEP – Sleep mode configured between transmitted bytes

RXSLEEP – Sleep mode configured between received bytes

RXSTOP – Stop mode configured between received bytes

HSI – Sets the system clock to 4MHz HSI mode.

RCC_MSIRANGE_SET – In case of HSI disabled, sets the MSI speed range.

7.3

Example operation

With UI disabled the boards start exchanging messages in the endless loop. In case of

communication error and debugging enabled, the loop is halted.

With UI option the boards will wait for user button press to start the loop and flash the LED

to indicate activity but all that has significant influence on the current consumption and UI

should be disabled for all power measurements.

AN4635 Datasheet(PDF) 31 Page - STMicroelectronics