1. Programming Microcontroller GPIO – General Purpose Input/Output
Programming and GPIO
2- 1
Programming Microcontroller
GPIO – General Purpose Input/Output
Week 1 – Spring Term 2017
32K Byte Burst Flash
64K or 96K Byte SRAM
256K or 512K Byte Burst Flash
OTP Mem
UART
I2C
SPI
TIM
RTC
EXT. Bus
GPIO
USB 2.0FS
CAN 2.0B
Enet MAC
PFQ BC
DMA
INTR Cntl
ARM966E
CORE
w/DSP
96 MHz
CLK Cntl
ADC
LVD BOD
PLL
JTAG
ETM9

2. A GPIO is a digital binary signal
Definition
Programming and GPIO
2- 2
A GPIO is a digital binary signal
Its switching level depends on the technology used
A GPIO normally is programmable as unconnected, input, output
A GPIO might have built-in elements like pull-up, pull-down or ESD (Electrostatic Discharge) devices
A GP Output signal is able to sink (or source) a defined amount of current
A GP Input has a defined Impedance which might be taken into account if a passive sensor is linked to it
A GP Input has a defined hysteresis to avoid "flippering" of the signal "Schmitt Trigger input"

3. STM32F40x Packages STM32F40x are furnished with the following packages
Programming and GPIO
STM32F40x Packages
2- 3
STM32F40x are furnished with the following packages
LQFP64 (pins)
LQFP100 (pins)
LQFP144 (pins)
LQFP176 (pins)
UFBGA176 (ball)
WLCSP90 (ball)
LQFP176 contains 9 ports with 16 pins
Ports are named alphabetically from PA to PI
Pins are identified numerically from 0 to 15

4. STM32F40x pin and ball definitions
Programming and GPIO
2- 4
Reference: page 45/185 of “STM32F405xx STM32F407xx” “Datasheet – production data”

5. GPIO pin assignment for peripherals
Programming and GPIO
GPIO pin assignment for peripherals
2- 5
Each GPIO pin can be assigned to a given number of peripheral modules
Register GPIOx_AFRL & GPIOx_AFRH enable to chose one of the sixteen alternatives
Reference: page 272/1745 of “RM0090 Reference manual”

6. GPIO signal flow Reference: page 268/1745 of “RM0090 Reference manual”
Programming and GPIO
GPIO signal flow
2- 6
Reference: page 268/1745 of “RM0090 Reference manual”

7. GPIO Configuration Registers
Programming and GPIO
2- 7
GPIOx_MODER – input, output, alternate function or analog mode
GPIOx_AFRH & GPIOx_AFRL - one of the sixteen alternate functions
GPIOx_OTYPER - push-pull or open drain
GPIOx_PUPDR - no pull-up, pull-up or pull-down
GPIOx_IDR - input data register
GPIOx_ODR - output data register

8. GPIO registers (first part)
Programming and GPIO
2- 8
GPIO registers (first part)
Reference
Page 286/1745 of “RM0090 Reference manual”

9. GPIO registers (second part)
Programming and GPIO
2- 9
GPIO registers (second part)
Reference
Page 286/1718 of “RM0090 Reference manual”

10. ARM High performance Bus 1 access (AHB1)
Programming and GPIO
2- 10
Reference
Page 71/185 of “STM32F405xx STM32F407xx” “Datasheet – production data”

11. ARM Peripheral Bus 1 access (APB1)
Programming and GPIO
2- 11
ARM Peripheral Bus 1 access (APB1)
Reference
Page 73/185 of “STM32F405xx STM32F407xx” “Datasheet – production data”

12. ARM Peripheral Bus 2 access (APB2)
Programming and GPIO
ARM Peripheral Bus 2 access (APB2)
2- 12
Reference
Page 72/185 of “STM32F405xx STM32F407xx” “Datasheet – production data”