Last year STMicro introduced the STM32 F4
family of high-performance ARM Cortex-M4 microcontrollers. They are now launching the F3 series, a
lower cost family of Cortex-M4 microcontrollers.
What is Cortex-M4? It is the 32bit ARM microcontroller heart of
these single chip computers. It differs
from the Cortex-M3 and Cortex-M0 in that it has an added floating point unit (FPU)
to perform faster floating point calculations.
It also has instructions intended to speed up digital signal processing
(DSP) and digital signal control applications such as single-cycle
multiply-accumulate (MAC) instructions, saturating arithmetic instructions, and
SIMD (single instruction, multiple data) instructions to speed data
processing. Details on the Cortex–M4
can be found on the ARM web site Cortex-M4 page
(click on the Specifications and Technology tabs).
The F3 family is intended for DSP/control
applications that do not require the large memories or the interface options of
the F4 family. The Cortex-M4 core
provides the same DSP and single-precision floating point instructions as found
in the F4 series. However, the F3
reduces the cost by removing memory and some of the communications interfaces of the F4’s
(such as Ethernet) while adding some new analog features.
The new analog features include 5
megasample-per-second ADCs, 16-bit sigma-delta ADCs, programmable gain
amplifiers, comparators, and three DACs on some versions. Some models have four ADCs with up to 39
input channels.
Discovery-F3 Module
A new discovery board is being distributed to support the new device. It provides a STM32F303VC microcontroller with 256k of Flash memory and 48k RAM. The module has the same two 50-pin DIL headers as the Discovery-F4 board, but the pinout is slightly different. The built-in STlinkV2 SWD programmer/debugger allows code to be downloaded and debugged without additional hardware. Also provided on the Discovery-F3 board are the L3GD20 3-axis digital gyroscope and LSM303DLHC 6-axis geomagnetic module. Details on the Discovery-F3 can be found on the STMicro web site Discovery-F3 page. To get a Discovery-F3 module in North America, attend one of the STM32 F3 North American Seminars in November and December 2012.Kornak Technologies is developing a baseboard for the Discovery-F3 that breaks out the connectors to individual headers to speed the assembly of your prototype system.
STM32 F3 and F4 Family Comparison
The following table contrasts the similarities and differences between the F3 and F4 families.
STM32 F3 Family,
Analog with DSP
|
STM32 F4 Family,
High-Performance DSP, with Connectivity
and Crypto
|
|
ARM Core
|
Cortex-M4
|
Cortex-M4
|
MCU Frequency
|
72 MHz
|
168 MHz
|
Floating Point Unit
|
Single precision FPU
IEEE 754 compliant |
Single precision FPU
IEEE 754 compliant |
Pins
|
48 to 100 pins
|
64 to 176 pins
|
Flash Memory
|
64k to 256k
|
512k to 1024k
|
SRAM
|
16 to 48k (some with parity checking)
|
196k
|
ADCs
|
9 to 39 channels, 1 to 4 ADCs
|
13 to 24 channels, 3 ADCs
|
16bit sigma-delta ADCs
|
Yes, on STM32F37x devices and STM32F38x
devices, 1 to 3
|
None
|
DACs
|
Yes, 1 to 3
|
Yes, 2
|
PGA (programmable gain amp)
|
Yes, up to 4
|
None
|
Analog Comparators
|
Yes, up to 7
|
None
|
Ethernet (10/100 Mbps)
|
None
|
Yes, on STMF4x7 devices
|
FSMC Ext Memory Interface
|
None
|
Yes, on 100pin or more devices
|
USART/UART
|
3 or 5 USARTs
|
4 USARTs + 2 UARTs
|
SPI
|
2 or 3 SPI
|
3 SPI
|
I2C
|
2 I2C
|
3 I2C
|
USB
|
Yes, 1 USB FS
|
Yes, 2, USB OTG (1 FS + 1 HS)
|
Crypto Processor
|
None
|
Yes, on STM32F41x devices
|
Random Number Generator
|
None
|
Yes
|
CRC Calculation Unit
|
Yes
|
Yes
|
Camera Interface
|
None
|
Yes, on STMF4x7 devices
|
To see which chips offer which mix of features, please download and view these Excel spreadsheets. I find it helpful to color the cells of the features I am interested in and sort on the key parameter.
STM32 F3 Family - MCUs with DSP and Analog Functions
Kornak-STMicro STM32-F3 Product List 2012-10-15.xls
STM32 F4 Family - High-Performance MCUs with DSP for Connectivity and Crypto
Kornak-STMicro STM32-F4 Product List 2012-10-15.xls
Please send any comments or corrections to Kornak.BusBoard@gmail.com
