ST STM32 Series Installation and operating instructions

July 2011 Doc ID 018608 Rev 1 1/12
AN3364
Application note
Migration and compatibility guidelines
for STM32 microcontroller applications
1 Introduction
For designers of STM32 microcontroller applications, it is important to be able to easily
replace one microcontroller type by another one in the same product series. Migrating an
application to a different microcontroller is often needed, when product requirements grow,
putting extra demands on memory size, or increasing the number of I/Os. On the other
hand, cost reduction objectives may force you to switch to smaller components and shrink
the PCB area. This application note is written to help you and analyze the steps you need to
migrate from an existing STM32-based design to any one of the other microcontroller types
in the fast-growing STM32 series.
To save your time, this application note groups together all the most important information
and lists the vital aspects that you need to address.
All the information included here can also be extremely worthwhile in your first STM32
design, not immediately concerned by a migration project. Studying the issues now will help
you tackle any future requirement by designing for compatibility from the beginning. To use
this application note, general STM32 knowledge is required, you can learn it from the
STM32 series reference manual, the STM32 datasheets, and the STM32 Flash program
memory programming manuals.
This application note presents an overview of the whole STM32 series and presents a first
level view of the different aspects that are important to consider when planning a new design
or migrating. The microcontroller blocks and peripherals are grouped and identified either as
fully compatible or compatible with enhancements or presented by types of series.
However the details of the migration guidelines across STM32 series are documented in
separate documents. Please refer to either of the following two documents:
●AN3427 Migrating applications from STM32F1 series to STM32F2 series
●AN3422 Migrating applications from STM32F1 series to STM32L1 series.
www.st.com

Contents AN3364
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Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 How to migrate across STM32 series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 STM32 series general overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1 STM32 product series feature comparison . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.2 STM32 product cross-compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Software migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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2 How to migrate across STM32 series
2.1 STM32 series general overview
The STM32 platform forms a strong foundation with a broad and growing portfolio. With new
products addressing new applications, the complete STM32 product series now comprises
three series, STM32F-1, STM32F-2 and STM32L-1, each dedicated to a specific segment:
●STM32 F-1:The general-purpose F-1 series addresses a wide range of applications,
from the lowest, price-sensitive designs to computing-intensive, high memory footprint
ones.
The F-1 series is a complete series whose members are fully pin-to-pin, software and
feature compatible.
–Low-density devices are STM32F101xx and STM32F103xx microcontrollers
where the Flash memory density ranges between 16 and 32 Kbytes.
–Medium-density devices are STM32F101xx and STM32F103xx microcontrollers
where the Flash memory density ranges between 32 and 128 Kbytes.
–High-density devices are STM32F101xx and STM32F103xx microcontrollers
where the Flash memory density ranges between 256 and 512 Kbytes.
– XL-density devices are STM32F101xx and STM32F103xx microcontrollers where
the Flash memory density ranges between 768 Kbytes and 1024 Kbyte.
–Connectivity-line devices are STM32F105xx and STM32F107xx microcontrollers
where the Flash memory density ranges between 64 and 256 Kbytes.
–Medium-density value line device is STM32F100xx microcontrollers where the
Flash memory density ranges between 64 and 128 Kbytes
–High-density value line device is STM32F100xx microcontrollers where the
Flash memory density ranges between 128 and 512 Kbytes.
●STM32 F-2:The F-2 series provides the highest performance for computing-intensive
applications and advanced connectivity. The F2 series maintains compatibility with the
F1 series.
●STM32 L-1: Designed for ultra-low-power applications that are energy-aware and seek
to achieve the absolute lowest power consumption. The L-1 series maintains
compatibility with the F1 series.
In the rest of this document (unless otherwise specified),
– the terms F1, STM32 F1 and STM32F10x are used to refer to the STM32 F-1
series
– the terms F2, STM32 F2 and STM32F2xx are used to refer to the STM32 F-2
series
– the terms L1, STM32 L1 and STM32L1xx are used to refer to the STM32 L-1
series

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2.1.1 STM32 product series feature comparison
Table 1. STM32 series overview
Peripheral STM32 F-1 Series STM32 L-1 Series STM32 F-2 Series
Core Cortex-M3 r1p1
MPU in XL-density only Cortex-M3 r2p0 w/ MPU Cortex-M3 r2p0 w/ MPU
FLASH memory 16 / 32 / 64 / 128 / 256 / 384 /
512 / 768KB - 1 MB 64/128 KB 128 / 256 / 512 / 768 /
1024 KB
SRAM 6 / 10 / 20 / 24 / 32 / 48 / 64 /
96 KB 10/16 KB
64/96/128 KB
+ 4KB backup SRAM
(can be used as
EEPROM memory)
OTP No No Yes (512 Bytes)
FSMC Ye s N o Ye s
Max CPU frequency
24 / 36 / 48 / 72 MHz
depending on the product
line used
32 MHz 120 MHz
Operating voltage 2.0 to 3.6 V 1.65 to 3.6 V 1.8(1) to 3.6 V
Bootloader (2)
Connectivity Line:
USART1/2, CAN2, DFU
(OTG FS Device)
Other product lines: USART1
USART1/2 USART1/3, CAN2, DFU
(OTG FS Device)
Timers
Advanced up to 2 No 2
General purpose up to 4 3 4
Basic up to 2 2 2
2 Channels up to 2 1 2
1 Channel up to 4 2 4
RTC Counter Hardware calendar Hardware calendar
COMs
SPI(I2S) up to 3(2) 2 3(2)
TI mode No No Yes
Max freq up to 18 Mbits/s up to16 Mbits/s up to 15 or 30 Mbits/s
Audio freq 8 kHz up to 96 kHz No 8 kHz up to 192 kHz

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COMs
I2C up to 2 2 3
Max freq 400 KHz 400 KHz 400 KHz
USART up to 3 3 4
UART up to 2 No 2
Max baud rate 2.25 or 4.5 Mbit/s up to 4 Mbit/s 3.75 or 7.5 Mbit/s
USB USB Device FS USB Device FS OTG FS
OTG FS OTG HS
CAN up to 2 No 2
SDIO 1No1
CEC up to 1 No No
Ethernet MAC Yes w/ HW IEEE 1588 v1 No Yes w/ HW IEEE1588 v2
GPIOs 26/37/51/80/112 37/51/83 51/82/114/140
12 bit ADC up to 3 1 3
Max Sampling freq 1 MSPS 1 MSPS 2 MSPS
Number of channels 10/16/21 channels 16/20/24 channels 16/24 Channels
12 bit DAC 222
Max Sampling freq 1 MS/s 1 MS/s 1 MS/s
Number of channels 222
DCMI No No Yes
Crypto/hash processor No No
Ye s
DES, 3DES, AES 256-bit
SHA-1, MD5, HMAC
Table 1. STM32 series overview (continued)
Peripheral STM32 F-1 Series STM32 L-1 Series STM32 F-2 Series

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RNG No No Yes
Package
VFQFPN36
LQFP48 LQFP48
VFQFPN48 VFQFN48
LQFP64 LQFP64 LQFP64
BGA64
WLCSP64 WLCSP64
TFBGA64
LQFP100 LQFP100 LQFP100
BGA100 BGA100
LFBGA100
LQFP144 LQFP144
BGA144
UFBGA176
1. If IRROFF is set to VDD on STM32F20xx devices, this value can be lowered to 1.65 V when the device operates in a
reduced temperature range.
2. For more information, please refer to application note AN2606 STM32 microcontroller system memory boot mode.
Table 1. STM32 series overview (continued)
Peripheral STM32 F-1 Series STM32 L-1 Series STM32 F-2 Series

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2.1.2 STM32 product cross-compatibility
The STM32 series embeds a set of peripherals which can be classed in three categories:
●The first category is for the peripherals which are by definition common to all products.
Those peripherals are identical, so they have the same structure, registers and control
bits. There is no need to perform any firmware change to keep the same functionality at
the application level after migration. All the features and behavior remain the same.
●The second category is for the peripherals which are shared by all products but have
only minor differences (in general to support new features), so migration from one
product to another is very easy and does not need any significant new development
effort.
●The third category is for peripherals which have been considerably changed from one
product to another (new architecture, new features...). For this category of peripherals,
migration will require new development at application level.
Table 2 below gives a general overview of this classification:
Table 2. STM32 peripheral compatibility analysis F1 versus F2 series
Peripheral F1 series F2 series
Compatibility
Comments Pinout SW compatibility
FSMC Yes Yes Same features Identical Full compatibility
WWDG Ye s Yes Same features NA Full compatibility
IWDG Ye s Yes Same features NA Full compatibility
DBGMCU Ye s Yes Same features NA Full compatibility
CRC Ye s Yes Same features NA Full compatibility
EXTI Ye s Yes Same features Identical Full compatibility
CAN Ye s Yes Same features Identical Full compatibility
PWR Ye s Ye s + Enhancement NA Full compatibility for
the same feature
RCC Ye s Ye s + Enhancement NA Partial compatibility
SPI Ye s Ye s + TI mode / Max baudrate Identical Full compatibility for
the same feature
USART Ye s Ye s +
Limitation fix / Max baudrate /
One Sample Bit / Oversampling
by 8
Identical Full compatibility for
the same feature
I2C Ye s Ye s + Limitation fix Identical Full compatibility for
the same feature
TIM Ye s Ye s + 32-bit Counter in TIM2 and
TIM5 Identical Full compatibility for the same feature
DAC Ye s Ye s + DMA underrun interrupt Identical Full compatibility for
the same feature

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Ethernet Ye s Ye s + IEEE1588 v2 / Enhanced DMA
descriptor Identical Full compatibility for
the same feature
SDIO Ye s Ye s + Limitation fix Identical Full compatibility for
the same feature
USB OTG FS Ye s Ye s +
- Dynamic trimming capability of
SOF framing period in Host
mode
- Embeds a VBUS sensing
control
Identical Full compatibility for
the same feature
RTC Ye s Yes++ New peripheral Identical for the
same feature Not compatible
ADC Ye s Yes++ New peripheral Identical for the
same feature Partial compatibility
FLASH Ye s Yes++ New peripheral NA Not compatible
DMA Ye s Yes++ New peripheral NA Not compatible
GPIO Ye s Yes++ New peripheral Identical Not compatible
CEC Ye s NA NA NA NA
USB FS
Device Ye s NA NA NA NA
Crypto/hash
processor NA Ye s NA NA NA
RNG NA Ye s NA NA NA
DCMI NA Ye s NA NA NA
USB OTG HS NA Ye s NA NA NA
SYSCFG NA Ye s NA NA NA
Table 2. STM32 peripheral compatibility analysis F1 versus F2 series (continued)
Peripheral F1 series F2 series
Compatibility
Comments Pinout SW compatibility
Color key:
= New feature or new architecture (Yes++)
= Same feature, but specification change or enhancement (Yes+)
= Feature not available (NA)

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Table 3. STM32 peripheral compatibility analysis F1 versus L1 series
Peripheral F1 series L1 series
Compatibility
Comments Pinout SW compatibility
SPI Ye s + Ye s No I2S in L1 series
L1 vs. F1: limitation fix Identical Full compatibility
WWDG Ye s Yes Same features NA Full compatibility
IWDG Ye s Yes Same features NA Full compatibility
DBGMCU Ye s Yes Same features NA Full compatibility
CRC Ye s Yes Same features NA Full compatibility
EXTI Ye s Yes Same features Identical Full compatibility
USB FS
Device Ye s Yes Same features Identical Full compatibility
DMA Ye s Yes Same features NA Full compatibility
TIM Ye s Yes Same features Identical Full compatibility
PWR Ye s Ye s + Enhancement NA Full compatibility for the
same feature
RCC Ye s Ye s + Enhancement NA Partial compatibility
USART Ye s Ye s +
Limitation fix / One Sample
Bit method / Oversampling by
8
Identical Full compatibility
I2C Ye s Ye s + Limitation fix Identical Full compatibility
DAC Ye s Ye s + DMA underrun interrupt Identical Full compatibility
ADC Ye s Yes++ New peripheral Identical Partial compatibility
RTC Ye s Yes++ New peripheral Identical for the
same feature Not compatible
FLASH Ye s Yes++ New peripheral NA Not compatible
GPIO Ye s Yes++ New peripheral Identical Not compatible
CAN Ye s NA NA NA NA
CEC Ye s NA NA NA NA
Ethernet Ye s NA NA NA NA
SDIO Ye s NA NA NA NA
FSMC Ye s NA NA NA NA
LCD glass NA Ye s NA NA NA

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2.2 Software migration
Each STM32 series is supported by a complete range of high-end and low-cost evaluation,
software, debugging and programming tools.
This complete line includes third-party solutions that come complete with an integrated
development environment and in-circuit debugger/programmer featuring a JTAG application
interface. Developers who are new to this series and the Cortex™ core can also benefit from
the range of starter kits that are specially designed to help developers evaluate device
features and start their own applications.
Thanks to ST firmware libraries and a comprehensive set of application notes, STM32
microcontrollers offer a complete software interface to reduce the time to market and keep
the user code independent from hardware details. The state-of-the-art and highly efficient
library of software drivers combined with extensive support for all major tool providers offers
a fast route to best-fit and an optimized development process.
COMP NA Yes NA NA NA
SYSCFG NA Yes NA NA NA
Table 3. STM32 peripheral compatibility analysis F1 versus L1 series (continued)
Peripheral F1 series L1 series
Compatibility
Comments Pinout SW compatibility
Color key:
= New feature or new architecture (Yes++)
= Same feature, but specification change or enhancement (Yes+)
= Feature not available (NA)