STM32: Peripherals. Alberto Bosio November 29, Univeristé de Montpellier

Transcription

1 STM32: Peripherals Alberto Bosio Univeristé de Montpellier November 29, 2017

2 System Architecture 2

3 System Architecture S0: I-bus: This bus connects the Instruction bus of the Cortex-M4 core to the BusMatrix. This bus is used by the core to fetch instructions. The targets of this bus are the internal Flash memory, the SRAM and the CCM RAM. S1: D-bus: This bus connects the DCode bus (literal load and debug access) of the Cortex-M4 core to the BusMatrix. The targets of this bus are the internal Flash memory, the SRAM and the CCM RAM. S2: S-bus: This bus connects the system bus of the Cortex-M4 core to the BusMatrix. This bus is used to access data located in the peripheral or SRAM area. The targets of this bus are the SRAM, the AHB to APB1/APB2 bridges, the AHB IO port and the ADC. S3, S4: DMA-bus: This bus connects the AHB master interface of the DMA to the BusMatrix which manages the access of different Masters to Flash, SRAM and peripherals. 3

4 Memory map Peripherals are memory mapped 4

5 Memory map 5

6 Memory map 6

7 Memory map 7

8 Memory map 8

9 Reset and clock control (RCC) System clock (SYSCLK) selection: HSI clock: generated from an internal 8 MHz RC Oscillator RCC registers allow to enable the use of a particular peripheral When the peripheral clock is not active, the peripheral register values may not be readable by software and the returned value is always 0x0. RCC_AHBENR, RCC_APB1RSTR, RCC_APB2RSTR 9

10 Example: Using on board LEDs On which bus LEDs are connected? 10

11 Example: Using on board LEDs On which bus LEDs are connected? Read DATA SHEET! 11

12 Example: Using on board LEDs 12

13 Example: Using on board LEDs 13

14 Example: Using on board LEDs We have to use GPIOE connected to bus AHB Let us configure the correct RCC register: RCC_AHBENR How to write? (address) Which value? 14

15 Example: Using on board LEDs 15

16 Example: Using on board LEDs We have to write 1 on the bit 21 Address: base + offset base = 0x offset = 0x14 address = 0x

17 Example: Using on board LEDs Can you write the assembler code? 17

18 Example: Using on board LEDs Next steps are: Configure the GPIOE in output mode Write a value in order to switch on/off LEDs 18

19 Example: Using on board LEDs Configure the GPIOE in output mode: GPIO port mode register (GPIOx_MODER) Which value do you have to write? Which address? 19

20 Example: Using on board LEDs Write a value in order to switch on/off LEDs: Which value do you have to write? Which address? 20

21 Interrupts Nested vectored interrupt controller (NVIC) 74 maskable interrupt channels 16 programmable priority levels (4 bits of interrupt priority are used) Low-latency exception and interrupt handling Power management control Implementation of System Control Registers 21

22 Configuring Interrupts To configure a line as interrupt source, use the following procedure: Configure the corresponding mask bit in the EXTI_IMR register. Configure the Trigger Selection bits of the Interrupt line (EXTI_RTSR and EXTI_FTSR). Set the Interrupt Service Routine. Clear the pending request. 22

23 External and internal interrupt/event line mapping 36 interrupt/event lines are available: 8 lines are internal (including the reserved ones); the remaining 28 lines are external. The GPIOs are connected to the 16 external interrupt/event lines in the following manner: 23

24 External and internal interrupt/event line mapping 24

25 External and internal interrupt/event line mapping 25

26 Configuring Interrupts Configure the corresponding mask bit in the EXTI_IMR register: 26

27 Configuring Interrupts Configure the Trigger Selection bits of the Interrupt line (EXTI_RTSR) 27

28 Configuring Interrupts Configure the Trigger Selection bits of the Interrupt line (EXTI_FTSR) 28

29 Configuring Interrupts Set the Interrupt Service Routine (Vector Table) 29

30 Configuring Interrupts 30

31 Configuring Interrupts 31

32 Configuring Interrupts Clear the pending request. 32