JXM Nucleo-G071RB devboard

Development Board Power

The development board is powered by a 5V DC power supply from the MicroUSB connector installed on the Nucleo board. MicroUSB connector Must be connected to a computer or 5V power supply.

The 5V line is shared between the development board and the Nucleo board. The 3.3V supply voltage is generated from a 5V source using a linear regulator (LDO) installed on the Nucleo board or on the development board. An additional 3.3V LDO is installed on the debug board in order to avoid overloading the 3.3V regulator installed on the Nucleo board when connecting additional peripherals to the debug board and requiring a 3.3V supply voltage. The 3.3V source (LDO) is selected using the J5 jumper on the debug board:

Buttons and indication

Buttons are duplicated on the JXM-Nucleo-G071RB Rev 1.0 debug board: "BTN_FN" - user button, connected to +3.3V power line; "EXT_RESET" - hardware reset of the microcontroller and user LED "STATUS_LED".

To control the boot mode of the microcontroller, the "BOOT0" button is used, which controls the BOOT0 pin of the microcontroller: while holding down the "BOOT0" button during power-up or hardware reset of the microcontroller, the built-in STM32 bootloader is loaded, which allows you to write firmware via UART or I2C. When pressed, a high logic level is set at the BOOT0 input of the microcontroller.

Setting SLOT_ID

The module ID (SLOT_ID) is set by the voltage level at pin 4 of the JXM 8-PIN connector. There are two options for setting the SLOT_ID voltage:

1. Using jumper J7 "SLOT_ID_SEL" (only one jumper must be set to the position corresponding to the desired slot number)
2. From external source (JMCU motherboard) via JXM 8-PIN connector.

Switching the mode of setting the voltage source SLOT_ID is carried out using the jumper J11 "MODE SLOT ID":

RESET

Hardware reset of the microcontroller is carried out:

1. (Normal method) By applying a logical 0 to the RESET input of the microcontroller. This input is connected to the JXM_EXT_RESET input of the JXM 8-PIN connector and allows you to control the controller reset. This input is also connected to the "EXT_RESET" button.
2. The RESET In of the microcontroller can be redefined by software, which will make it impossible to control the reset in a regular way. To control the reset of the microcontroller in this case, the option of rebooting "by power" is provided. In this mode, the JXM_EXT_RESET input of the JXM 8-PIN connector is connected through a transistor to the EN LDO 3.3V pin on the debug board, which allows you to control the power supply of the microcontroller. The power is turned off by a high logic level at the JXM_EXT_RESET pin of the JXM 8-PIN connector. Switching the operating mode of the hardware reset is done by jumper J6:

Switching pin BOOT0

The BOOT0 button and the JXM_EXT_INT_BOOT pin are by default connected to the PA14 pin of the microcontroller, which is also used to connect the JTAG SWD_CLK.

There is a backup option to connect the JXM_EXT_INT_BOOT pin on the PA15 microcontroller. Switching is performed by jumper J8: in the position of the jumper 1-2, the JXM_EXT_INT_BOOT output is connected to the PA15 output of the microcontroller; in position 2-3 - to the output PA14 of the microcontroller (default position).

EEPROM and FRAM

Addresses of memory chips on the I2C bus:

EEPROM CAT24C64 64Kbit address 7-bit 0x54

FRAM FM24CL64B 64Kbit address 7-bit 0x52

JXM module pinout 8-pin connector

STM32G071RB pin assignment

Voltages and division ratios for analog inputs and outputs

Analog output 0 .. 10V

The JXM_PWM_2 analog output works with PWM at 500Hz and up to 10 .

It is optimal to use a frequency of 1 kHz. Filling from 1% to 90%.

1-Wire

1-Wire can be connected to TX or RX JXM_U1WIRE by soldering resistors.

By default, 1-Wire is connected to the JXM_U1WIRE_RX line (pin PA10 of the microcontroller).