stm32: peripherals - lirmm
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System Architecture
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System Architecture
S0: I-bus: This bus connects the Instruction bus of theCortex-M4 core to the BusMatrix. This bus is used by the coreto fetch instructions. The targets of this bus are the internalFlash memory, the SRAM and the CCM RAM.S1: D-bus: This bus connects the DCode bus (literal loadand debug access) of the Cortex-M4 core to the BusMatrix.The targets of this bus are the internal Flash memory, theSRAM and the CCM RAM.S2: S-bus: This bus connects the system bus of theCortex-M4 core to the BusMatrix. This bus is used to accessdata located in the peripheral or SRAM area. The targets ofthis bus are the SRAM, the AHB to APB1/APB2 bridges, theAHB IO port and the ADC.S3, S4: DMA-bus: This bus connects the AHB masterinterface of the DMA to the BusMatrix which manages theaccess of different Masters to Flash, SRAM and peripherals.
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Memory map
Peripherals are memory mapped
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Memory map
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Memory map
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Memory map
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Memory map
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Reset and clock control (RCC)
System clock (SYSCLK) selection:I HSI clock: generated from an internal 8 MHz RC Oscillator
RCC registers allow to enable the use of a particular peripheralI When the peripheral clock is not active, the peripheral register
values may not be readable by software and the returned valueis always 0x0.
RCC_AHBENR, RCC_APB1RSTR, RCC_APB2RSTR
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Example: Using on board LEDs
On which bus LEDs are connected?
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Example: Using on board LEDs
On which bus LEDs are connected? Read DATA SHEET!
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Example: Using on board LEDs
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Example: Using on board LEDs
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Example: Using on board LEDs
We have to use GPIOE connected to bus AHBLet us configure the correct RCC register: RCC_AHBENR
I How to write? (address)I Which value?
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Example: Using on board LEDs
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Example: Using on board LEDs
We have to write ‘1’ on the bit 21Address: base + offset
I base = 0x40021000I offset = 0x14I address = 0x40021014
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Example: Using on board LEDs
Can you write the assembler code?
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Example: Using on board LEDs
Next steps are:I Configure the GPIOE in output modeI Write a value in order to switch on/off LEDs
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Example: Using on board LEDs
Configure the GPIOE in output mode:I GPIO port mode register (GPIOx_MODER)
Which value do you have to write? Which address?
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Example: Using on board LEDs
Write a value in order to switch on/off LEDs:
Which value do you have to write? Which address?
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Interrupts
Nested vectored interrupt controller (NVIC)I 74 maskable interrupt channelsI 16 programmable priority levels (4 bits of interrupt priority are
used)I Low-latency exception and interrupt handlingI Power management controlI Implementation of System Control Registers
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Configuring Interrupts
To configure a line as interrupt source, use the followingprocedure:
I Configure the corresponding mask bit in the EXTI_IMRregister.
I Configure the Trigger Selection bits of the Interrupt line(EXTI_RTSR and EXTI_FTSR).
I Set the Interrupt Service Routine.I Clear the pending request.
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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 areexternal.The GPIOs are connected to the 16 external interrupt/eventlines in the following manner:
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External and internal interrupt/event line mapping
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External and internal interrupt/event line mapping
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Configuring Interrupts
Configure the corresponding mask bit in the EXTI_IMRregister:
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Configuring Interrupts
Configure the Trigger Selection bits of the Interrupt line(EXTI_RTSR)
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Configuring Interrupts
Configure the Trigger Selection bits of the Interrupt line(EXTI_FTSR)
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Configuring Interrupts
Set the Interrupt Service Routine (Vector Table)
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Configuring Interrupts
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Configuring Interrupts
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Configuring Interrupts
Clear the pending request.