ST STM32F0 Series Application Note
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ST STM32F0 Series Application Note

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Getting started with STM32F0xxx hardware development
Introduction
This application note is intended for system designers who require a hardware
implementation overview of the development board features such as the power supply, the
clock management, the reset control, the boot mode settings and the debug management. It
shows how to use the STM32F0xxx product family and describes the minimum hardware
resources required to develop an STM32F0xxx application.
The STM32F0xxx family comprises a sub-group, the STM32F06xxx, which can be
distinguished from the main devices (STM32F05xxx). This sub-family bypasses the internal
voltage regulator to target applications that already have one onboard.
Detailed reference design schematics are also contained in this document with descriptions
of the main components, interfaces and modes.
Table 1.
Microcontrollers
February 2013
Applicable products
Type
Doc ID 023035 Rev 2
Application note
Part number
STM32F05xxx family
STM32F06xxx family
AN4080
1/29
www.st.com

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  • Page 1 Detailed reference design schematics are also contained in this document with descriptions of the main components, interfaces and modes. Table 1. Applicable products Type Part number STM32F05xxx family Microcontrollers STM32F06xxx family February 2013 Doc ID 023035 Rev 2 1/29 www.st.com...

  • Page 2: Table Of Contents

    Contents AN4080 Contents Power supplies of the STM32F05xxx family ..... . 4 Power supply schemes ........4 1.1.1 Independent analog converter supply .
  • Page 3 AN4080 Contents 5.3.2 SWD pin assignment ........20 5.3.3 Internal pull-up and pull-down on SWD pins .

  • Page 4: Power Supplies Of The Stm32F05Xxx Family

    Power supplies of the STM32F05xxx family AN4080 Power supplies of the STM32F05xxx family Power supply schemes There are a variety of power supply schemes: ● = 2.0 to 3.6 V: external power supply for I/Os and the internal regulator. Provided externally through V pins.

  • Page 5: Independent Analog Converter Supply

    AN4080 Power supplies of the STM32F05xxx family 1.1.1 Independent analog converter supply To improve conversion accuracy and to extend the supply flexibility, the analog domain has an independent power supply which can be separately filtered and shielded from noise on the PCB.
  • Page 6 Power supplies of the STM32F05xxx family AN4080 It works in three different modes depending on the application modes: ● Run mode: the regulator supplies full power to the 1.8 V domain (core, memories and digital peripherals) ● Stop mode: the regulator supplies low power to the 1.8 V domain, preserving the contents of the registers and SRAM ●...

  • Page 7: Reset And Power Supply Supervisor

    AN4080 Power supplies of the STM32F05xxx family Reset and power supply supervisor 1.2.1 Power-on reset (POR) / power-down reset (PDR) The device has an integrated power-on reset (POR) and power-down reset (PDR) circuits which are always active and ensure proper operation above a threshold of 2 V. The device remains in Reset mode when the monitored supply voltage is below a specified threshold, V , without the need for an external reset circuit.

  • Page 8: System Reset

    Power supplies of the STM32F05xxx family AN4080 1.2.2 System reset A system reset sets all registers to their reset values, except the reset flags in the clock controller CSR register and the registers in the Backup domain. A system reset is generated when one of the following events occurs: A low level on the NRST pin (external reset).
  • Page 9 AN4080 Power supplies of the STM32F05xxx family Low-power management reset There are two ways to generate a low-power management reset: Entering Standby mode: This type of reset is enabled by resetting nRST_STDBY bit in User Option Bytes. In this case, whenever a Standby mode entry sequence is successfully executed, the device is reset instead of entering Standby mode.

  • Page 10: Programmable Voltage Detector (Pvd)

    Power supplies of the STM32F05xxx family AN4080 1.2.3 Programmable voltage detector (PVD) You can use the PVD to monitor the V power supply by comparing it to a threshold selected by the PLS[2:0] bits in the Power control register (PWR_CR). The PVD is enabled by setting the PVDE bit.

  • Page 11: Power Supplies Of The Stm32F06Xxx Family

    AN4080 Power supplies of the STM32F06xxx family Power supplies of the STM32F06xxx family Power supply schemes There are a variety of power supply schemes: ● = 1.8 V +/- 8%: external power supply for I/Os. Provided externally through V pins. ●...

  • Page 12: Independent Analog Converter Supply

    Power supplies of the STM32F06xxx family AN4080 2.1.1 Independent analog converter supply To improve conversion accuracy and to extend the supply flexibility, the analog domain has an independent power supply which can be separately filtered and shielded from noise on the PCB.

  • Page 13: Reset And Power Supply Supervisor

    AN4080 Power supplies of the STM32F06xxx family Reset and power supply supervisor 2.2.1 External power-on reset and power-down reset (NPOR) To guarantee a proper power-on and power-down reset to the device, the NPOR pin must be held low until V is stable or before turning off the supply.
  • Page 14 Power supplies of the STM32F06xxx family AN4080 Low-power management reset A low-power management reset can be generated by entering Stop mode. This type of reset is enabled by resetting nRST_STOP bit in User Option Bytes. In this case, whenever a Stop mode entry sequence is successfully executed, the device is reset instead of entering Stop mode.

  • Page 15: Clocks

    AN4080 Clocks Clocks Three different clock sources can be used to drive the system clock (SYSCLK): ● HSI 8 MHz RC oscillator clock (high-speed internal clock signal) ● HSE oscillator clock (high-speed external clock signal) ● PLL clock The devices have other secondary clock sources: ●...

  • Page 16: Lse Clock

    Clocks AN4080 External crystal/ceramic resonator (HSE crystal) The 4 to 32 MHz external oscillator has the advantage of producing a very accurate rate on the main clock. Refer to the electrical characteristics section of the datasheet for more details about the associated hardware configuration. The HSERDY flag in the Clock control register (RCC_CR) indicates if the HSE oscillator is stable or not.

  • Page 17: Lsi Clock

    Calibration RC oscillator frequencies can vary from one chip to another due to manufacturing process variations, This is why each device is factory calibrated by ST for 1% accuracy at T =25°C. Furthermore, it is possible to route the HSI clock to the MCO multiplexer. The clock can then be input to Timer 14 to allow the user to calibrate the oscillator.

  • Page 18: Boot Configuration

    0000), but is still accessible from its original memory space (0x2000 0000). Embedded boot loader The embedded boot loader is located in the System memory, programmed by ST during production. It is used to reprogram the Flash memory using one of the following serial interfaces: ●...

  • Page 19: Debug Management

    Figure 10 shows the connection of the host to the evaluation board (STM320518_EVAL). The STM320518_EVAL evaluation board embeds the debug tools (ST-LINK). Consequently, it can be directly connected to the PC through a USB cable. Figure 10. Host-to-board connection...

  • Page 20: Swd Pin Assignment

    Debug management AN4080 5.3.2 SWD pin assignment After reset (SYSRESETn or PORESETn), the pins used for the SWD are assigned as dedicated pins which are immediately usable by the debugger host. However, the MCU offers the possibility to disable the SWD, therefore releasing the associated pins for general-purpose I/O (GPIO) usage.

  • Page 21: Recommendations

    AN4080 Recommendations Recommendations Printed circuit board For technical reasons, it is best to use a multilayer printed circuit board (PCB) with a separate layer dedicated to ground (V ) and another dedicated to the V supply. This provides good decoupling and a good shielding effect. For many applications, economical reasons prohibit the use of this type of board.

  • Page 22: Other Signals

    Recommendations AN4080 Figure 12. Typical layout for V pair Via to V Via to V Cap. STM32F0xxx Other signals When designing an application, the EMC performance can be improved by closely studying: ● Signals for which a temporary disturbance affects the running process permanently (such as interrupts and handshaking strobe signals, but not LED commands).

  • Page 23: Reference Design

    AN4080 Reference design Reference design Description The reference design shown in Figure 13, introduces the STM32F051, a highly integrated ™ microcontroller running at 48 MHz, that combines the Cortex -M0 32-bit RISC CPU core with 64 Kbytes of embedded Flash memory and 8 Kbytes of SRAM For the STM32F061 reference designs, refer to Figure 14.

  • Page 24: Pinouts And Pin Description

    Reference design AN4080 7.1.7 Pinouts and pin description Please refer to the STM32F0 datasheets available on www.st.com for the pinout information and pin description of each device. Component references Table 4. Mandatory components Component Reference Value Quantity Comments STM32F051R8 or...
  • Page 25 AN4080 Reference design Figure 13. STM32F051R8 microcontroller reference schematic SWD connector CN 1 FTSH - 105-01-L-DV STM32 F 051R8 T6 Boot mode PA14 VDD_ 2 PA15 VSS_ 2 PC10 PB11 PC11 PB10 PC12 BOOT 0 VSS_ 1 VDD_ 1 Battery VDD A BT 1 JP12...
  • Page 26 Reference design AN4080 Figure 14. STM32F061R8 microcontroller reference schematic SWD connector CN 1 FTSH - 105-01-L-DV STM32 F 061R8 T6 Boot mode PA14 VDD_ 2 PA15 VSS_ 2 PC10 PB11 PC11 PB10 PC12 NPOR NPOR signal BOOT 0 VSS_ 1 VDD_ 1 Battery VDD A...

  • Page 27: Hardware Migration From Stm32F1 To Stm32F0

    All peripherals shares the same pins in the two families, but there are some minor differences between packages. The transition from the STM32F1 series to the STM32F0 series is simple as only a few pins are impacted (impacted pins are in bold in Table Table 6.

  • Page 28: Revision History

    Document revision history Date Revision Changes 11-Jul-2012 Initial release. Added Chapter 2: Power supplies of the STM32F06xxx family. Modified Chapter 7: Reference design. 11-Feb-2013 Modified Table 6: STM32F1 series and STM32F0 series pinout differences. 28/29 Doc ID 023035 Rev 2...
  • Page 29 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.

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