Interrupts AXI GPIO and AXI Timer ECE 699: Lecture 4

InterruptsAXI GPIO and AXI Timer

ECE 699: Lecture 4

Required Reading

• Tutorial 2: Next Steps in Zynq SoC DesignThe ZYNQ Book Tutorials

• Section 13: Basic I/O

ZYBO Reference Manual

LogiCORE IP AXI GPIO Product Specification

LogiCORE IP AXI GPIO v2.0 Product Guide

LogiCORE IP AXI Timer v2.0 Product Guide

• Chapter 7: Interrupts

Zynq-7000 All Programmable SoC – Technical Reference Manual

Recommended Reading

• Chapter 10.4: Interrupts

The ZYNQ Book

ARM Generic Interrupt Controller – Architecture Specification

• Chapter 1: Introduction• Chapter 2: GIC Partitioning• Chapter 3: Interrupt Handling and Prioritization• Chapter 4: Programmers’ Model

ZYBO Board

Source: ZYBO Reference Manual

ZYBO Board Components


Class Exercise 1:

Modifying a Counter Using Pushbuttons

Class Exercise 2:

Modifying a Counter Using AXI Timer

(every N ms)

ZYBO General Purpose Input Output (GPIO)


AXI GPIO Core Connected to Buttons

AXI Timer Core Implemented in Programmable Logic

Mapping of an Embedded SoC Hardware Architecture to Zynq

Source: Xilinx White Paper: Extensible Processing Platform

A Simplified Model of the Zynq Architecture

Source: The Zynq Book

btns

leds

DDRFIXED_IO

Block Design for Class Exercise 1

btns

leds

DDRFIXED_IO


btns

leds

DDRFIXED_IO


btns

leds

DDRFIXED_IO


Block Diagram of AXI GPIO

IPIC – IP Interconnect interface

enabled only when the C_INTERRUPT_PRESENTgeneric set to 1

Source: LogiCORE IP AXI GPIO: Product Specification

Setting GPIO Core Parameters in Vivado

4

GPIO Core






AXI Interconnects and Interfaces

Source: The Zynq Book

Constraints File

entity design_int_wrapper is port ( DDR_addr : inout STD_LOGIC_VECTOR ( 14 downto 0 ); DDR_ba : inout STD_LOGIC_VECTOR ( 2 downto 0 ); DDR_cas_n : inout STD_LOGIC; DDR_ck_n : inout STD_LOGIC; DDR_ck_p : inout STD_LOGIC; DDR_cke : inout STD_LOGIC; DDR_cs_n : inout STD_LOGIC; DDR_dm : inout STD_LOGIC_VECTOR ( 3 downto 0 ); DDR_dq : inout STD_LOGIC_VECTOR ( 31 downto 0 ); DDR_dqs_n : inout STD_LOGIC_VECTOR ( 3 downto 0 ); DDR_dqs_p : inout STD_LOGIC_VECTOR ( 3 downto 0 ); DDR_odt : inout STD_LOGIC; DDR_ras_n : inout STD_LOGIC; DDR_reset_n : inout STD_LOGIC; DDR_we_n : inout STD_LOGIC; FIXED_IO_ddr_vrn : inout STD_LOGIC; FIXED_IO_ddr_vrp : inout STD_LOGIC; FIXED_IO_mio : inout STD_LOGIC_VECTOR ( 53 downto 0 ); FIXED_IO_ps_clk : inout STD_LOGIC; FIXED_IO_ps_porb : inout STD_LOGIC; FIXED_IO_ps_srstb : inout STD_LOGIC; leds_tri_o : out STD_LOGIC_VECTOR ( 3 downto 0 ); btns_tri_i : in STD_LOGIC_VECTOR ( 3 downto 0 ) );end design_int_wrapper;

design_1_i: component design_1 port map ( DDR_addr(14 downto 0) => DDR_addr(14 downto 0), DDR_ba(2 downto 0) => DDR_ba(2 downto 0), DDR_cas_n => DDR_cas_n, DDR_ck_n => DDR_ck_n, DDR_ck_p => DDR_ck_p, DDR_cke => DDR_cke, DDR_cs_n => DDR_cs_n, DDR_dm(3 downto 0) => DDR_dm(3 downto 0), DDR_dq(31 downto 0) => DDR_dq(31 downto 0), DDR_dqs_n(3 downto 0) => DDR_dqs_n(3 downto 0), DDR_dqs_p(3 downto 0) => DDR_dqs_p(3 downto 0), DDR_odt => DDR_odt, DDR_ras_n => DDR_ras_n, DDR_reset_n => DDR_reset_n, DDR_we_n => DDR_we_n, FIXED_IO_ddr_vrn => FIXED_IO_ddr_vrn, FIXED_IO_ddr_vrp => FIXED_IO_ddr_vrp, FIXED_IO_mio(53 downto 0) => FIXED_IO_mio(53 downto 0), FIXED_IO_ps_clk => FIXED_IO_ps_clk, FIXED_IO_ps_porb => FIXED_IO_ps_porb, FIXED_IO_ps_srstb => FIXED_IO_ps_srstb, leds_tri_o(3 downto 0) => leds_tri_o(3 downto 0), btns_tri_o(3 downto 0) => btns_tri_i(3 downto 0) );



##LEDs##IO_L23P_T3_35set_property PACKAGE_PIN M14 [get_ports {leds_tri_o[0]}]set_property IOSTANDARD LVCMOS33 [get_ports {leds_tri_o[0]}]

##IO_L23N_T3_35set_property PACKAGE_PIN M15 [get_ports {leds_tri_o[1]}]set_property IOSTANDARD LVCMOS33 [get_ports {leds_tri_o[1]}]

##IO_0_35set_property PACKAGE_PIN G14 [get_ports {leds_tri_o[2]}]set_property IOSTANDARD LVCMOS33 [get_ports {leds_tri_o[2]}]

##IO_L3N_T0_DQS_AD1N_35set_property PACKAGE_PIN D18 [get_ports {leds_tri_o[3]}]set_property IOSTANDARD LVCMOS33 [get_ports {leds_tri_o[3]}]

ZYBO_Master.xdc (1)



##Buttons##IO_L20N_T3_34set_property PACKAGE_PIN R18 [get_ports {btn_tri_i[0]}]set_property IOSTANDARD LVCMOS33 [get_ports {btn_tri_i[0]}]

##IO_L24N_T3_34set_property PACKAGE_PIN P16 [get_ports {btn_tri_i[1]}]set_property IOSTANDARD LVCMOS33 [get_ports {btn_tri_i[1]}]

##IO_L18P_T2_34set_property PACKAGE_PIN V16 [get_ports {btn_tri_i[2]}]set_property IOSTANDARD LVCMOS33 [get_ports {btn_tri_i[2]}]

##IO_L7P_T1_34set_property PACKAGE_PIN Y16 [get_ports {btn_tri_i[3]}]set_property IOSTANDARD LVCMOS33 [get_ports {btn_tri_i[3]}]

ZYBO_Master.xdc (3)

Interrupts






Global Interrupt Enable, GIER


Interrupt Enable Registers, IP IER


Interrupt Status Registers, IP ISR

StatusStatus


Addresses of Interrupt-Related AXI GPIO Registers


AXI GPIO Resource Utilization andMaximum Clock Frequency

AXI Timer

1. Generating delays - imposing a specific delay between two points in the program

label 1

label2

instr1instr2

instrN

delay

Functions of a Typical Timer (1)

2. Output compare - generating signals with the given timing characteristics

pulse width

single pulse periodical signal

period


3. Input capture - measuring the time between signal edges

start stop

start stop


Block Diagram of AXI Timer

Source: LogiCORE IP AXI Timer: Product Guide

AXI Timer: Modes of Operation

• Generate Mode

• Capture Mode

• Pulse Width Modulation Mode

• Cascade Mode

Generate Mode

• Counter when enabled begins to count up or down

• On transition of carry out, the counter

• stops, or

• automatically reloads the initial value from the load register,

and continues counting

• if enabled, GenerateOut is driven to 1 for one clock cycle

• if enabled, the interrupt signal for the timer is driven to 1

• Can be used to

• Generate repetitive interrupts

• One-time pulses

• Periodical signals

Capture Mode

• The counter can be configured as an up or down counter

• The value of the counter is stored in the load register when

the external capture signal is asserted

• The TINT flag is also set on detection of the capture event

• The Auto Reload/Hold (ARHT) bit controls whether the

capture value is overwritten with a new capture value

before the previous TINT flag is cleared

• Can be used to measure

• Widths of non-periodical signals

• Periods of periodical signals

• Intervals between edges of two different signals, etc.

Pulse Width Modulation (PWM) Mode

• Two timer/counters are used as a pair to produce an output

signal (PWM0) with a specified frequency and duty factor

• Timer 0 sets the period

• Timer 1 sets the high time for the PWM0 output

• Can be used to generate

• Periodical signals with varying period and duty cycle

Cascade Mode

• Two timer/counters are cascaded to operate as

a single 64-bit counter/timer

• The cascaded counter can work in both generate

and capture modes

• TCSR0 acts as the control and status register for the

cascaded counter. TCSR1 is ignored in this mode.

• Can be used to

• Generate longer delays

• Generate signals with larger pulse widths or periods

• Measure longer time intervals

Timer/Counter Register, TCR0, TCR1


Load Register, TLR0, TLR1

Control/Status Registers, TCSR0


Control/Status Register 0, TCSR0











Configuration of Zynq Processing System in Vivado

Configuration of Zynq Processing System in Vivado

System-Level Interrupt Environment

Source: Zynq-7000 All Programmable SoC –Technical Reference Manual

Class Exercise 1:

Modifying a Counter Using Pushbuttons

#include "xparameters.h"#include "xgpio.h"#include "xscugic.h"#include "xil_exception.h"#include "xil_printf.h"

// Parameter definitions#define INTC_DEVICE_ID XPAR_PS7_SCUGIC_0_DEVICE_ID#define BTNS_DEVICE_ID XPAR_AXI_GPIO_0_DEVICE_ID#define LEDS_DEVICE_ID XPAR_AXI_GPIO_1_DEVICE_ID#define INTC_GPIO_INTERRUPT_ID XPAR_FABRIC_AXI_GPIO_0_IP2INTC_IRPT_INTR

#define BTN_INT XGPIO_IR_CH1_MASK

C Program (1)

XGpio LEDInst, BTNInst;XScuGic INTCInst;static int led_data;static int btn_value;

//----------------------------------------------------// PROTOTYPE FUNCTIONS//----------------------------------------------------static void BTN_Intr_Handler(void *InstancePtr);static int InterruptSystemSetup(XScuGic *XScuGicInstancePtr);static int IntcInitFunction(u16 DeviceId, XGpio *GpioInstancePtr);

C Program (2)

void BTN_Intr_Handler(void *InstancePtr){ // Disable GPIO interrupts XGpio_InterruptDisable(&BTNInst, BTN_INT); // Ignore additional button presses if ((XGpio_InterruptGetStatus(&BTNInst) & BTN_INT) !=BTN_INT) { return; } btn_value = XGpio_DiscreteRead(&BTNInst, 1); // Increment counter based on button value // Reset if center button pressed if(btn_value != 8) led_data = led_data + btn_value; else led_data = 0; XGpio_DiscreteWrite(&LEDInst, 1, led_data); (void) XGpio_InterruptClear(&BTNInst, BTN_INT); // Enable GPIO interrupts XGpio_InterruptEnable(&BTNInst, BTN_INT);}

C Program (3)

int main (void){ int status; // Initialise LEDs status = XGpio_Initialize(&LEDInst, LEDS_DEVICE_ID); if(status != XST_SUCCESS) return XST_FAILURE; // Initialize Push Buttons status = XGpio_Initialize(&BTNInst, BTNS_DEVICE_ID); if(status != XST_SUCCESS) return XST_FAILURE; // Set LEDs direction to outputs XGpio_SetDataDirection(&LEDInst, 1, 0x00); // Set all buttons direction to inputs XGpio_SetDataDirection(&BTNInst, 1, 0xFF);

// Initialize interrupt controller status = IntcInitFunction(INTC_DEVICE_ID, &BTNInst); if(status != XST_SUCCESS) return XST_FAILURE; while(1); return 0;}

C Program (4)

int IntcInitFunction(u16 DeviceId, XGpio *GpioInstancePtr){ XScuGic_Config *IntcConfig; int status;

// Interrupt controller initialization IntcConfig = XScuGic_LookupConfig(DeviceId); status = XScuGic_CfgInitialize(&INTCInst, IntcConfig, IntcConfig->CpuBaseAddress); if(status != XST_SUCCESS) return XST_FAILURE;

// Call to interrupt setup status = InterruptSystemSetup(&INTCInst); if(status != XST_SUCCESS) return XST_FAILURE;

C Program (5)

// Connect GPIO interrupt to handler status = XScuGic_Connect(&INTCInst, INTC_GPIO_INTERRUPT_ID,

(Xil_ExceptionHandler) BTN_Intr_Handler, (void *)GpioInstancePtr);

if(status != XST_SUCCESS) return XST_FAILURE;

// Enable GPIO interrupts interrupt XGpio_InterruptEnable(GpioInstancePtr, 1); XGpio_InterruptGlobalEnable(GpioInstancePtr);

// Enable GPIO interrupts in the controller XScuGic_Enable(&INTCInst, INTC_GPIO_INTERRUPT_ID);

return XST_SUCCESS;}

C Program (6)

int InterruptSystemSetup(XScuGic *XScuGicInstancePtr){ // Enable interrupt XGpio_InterruptEnable(&BTNInst, BTN_INT); XGpio_InterruptGlobalEnable(&BTNInst);

Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT, (Xil_ExceptionHandler) XScuGic_InterruptHandler, XScuGicInstancePtr);

Xil_ExceptionEnable();

return XST_SUCCESS;

}

C Program (7)

Class Exercise 2:

Modifying a Counter Using AXI Timer

(every N ms)

#include "xparameters.h"#include "xgpio.h"#include "xtmrctr.h"#include "xscugic.h"#include "xil_exception.h"#include "xil_printf.h"

// Parameter definitions#define INTC_DEVICE_ID XPAR_PS7_SCUGIC_0_DEVICE_ID#define TMR_DEVICE_ID XPAR_TMRCTR_0_DEVICE_ID#define BTNS_DEVICE_ID XPAR_AXI_GPIO_0_DEVICE_ID#define LEDS_DEVICE_ID XPAR_AXI_GPIO_1_DEVICE_ID#define INTC_GPIO_INTERRUPT_ID XPAR_FABRIC_AXI_GPIO_0_IP2INTC_IRPT_INTR#define INTC_TMR_INTERRUPT_ID XPAR_FABRIC_AXI_TIMER_0_INTERRUPT_INTR

#define BTN_INT XGPIO_IR_CH1_MASK#define TMR_LOAD 0xF8000000

C Program (1)

XGpio LEDInst, BTNInst;XScuGic INTCInst;XTmrCtr TMRInst;static int led_data;static int btn_value;static int tmr_count;

//----------------------------------------------------// PROTOTYPE FUNCTIONS//----------------------------------------------------static void BTN_Intr_Handler(void *InstancePtr);static void TMR_Intr_Handler(void *InstancePtr);static int InterruptSystemSetup(XScuGic *XScuGicInstancePtr);static int IntcInitFunction(u16 DeviceId, XTmrCtr *TmrInstancePtr, XGpio *GpioInstancePtr);

C Program (2)

void BTN_Intr_Handler(void *InstancePtr){ // Disable GPIO interrupts XGpio_InterruptDisable(&BTNInst, BTN_INT); // Ignore additional button presses if ((XGpio_InterruptGetStatus(&BTNInst) & BTN_INT) !=BTN_INT) { return; } btn_value = XGpio_DiscreteRead(&BTNInst, 1); // Increment counter based on button value // Reset if center button pressed if(btn_value != 8) led_data = led_data + btn_value; else led_data = 0; XGpio_DiscreteWrite(&LEDInst, 1, led_data); (void) XGpio_InterruptClear(&BTNInst, BTN_INT); // Enable GPIO interrupts XGpio_InterruptEnable(&BTNInst, BTN_INT);}

C Program (3A)

void TMR_Intr_Handler(void *InstancePtr){

if (XTmrCtr_IsExpired(&TMRInst, 0)){// Once timer has expired 3 times, stop, increment

counter// reset timer and start running againif(tmr_count == 3){

XTmrCtr_Stop(&TMRInst, 0);tmr_count = 0;led_data++;XGpio_DiscreteWrite(&LEDInst, 1, led_data);XTmrCtr_Reset(&TMRInst, 0);XTmrCtr_Start(&TMRInst, 0);

}else tmr_count++;

}}

C Program (3B)

int main (void){ int status; // Initialise LEDs status = XGpio_Initialize(&LEDInst, LEDS_DEVICE_ID); if(status != XST_SUCCESS) return XST_FAILURE; // Initialize Push Buttons status = XGpio_Initialize(&BTNInst, BTNS_DEVICE_ID); if(status != XST_SUCCESS) return XST_FAILURE; // Set LEDs direction to outputs XGpio_SetDataDirection(&LEDInst, 1, 0x00); // Set all buttons direction to inputs XGpio_SetDataDirection(&BTNInst, 1, 0xFF);

C Program (4A)

//---------------------------------------------------- // SETUP THE TIMER //---------------------------------------------------- status = XTmrCtr_Initialize(&TMRInst, TMR_DEVICE_ID); if(status != XST_SUCCESS) return XST_FAILURE; XTmrCtr_SetHandler(&TMRInst, TMR_Intr_Handler, &TMRInst); XTmrCtr_SetResetValue(&TMRInst, 0, TMR_LOAD); XTmrCtr_SetOptions(&TMRInst, 0, XTC_INT_MODE_OPTION | XTC_AUTO_RELOAD_OPTION);

C Program (4A)

// Initialize interrupt controller status = IntcInitFunction(INTC_DEVICE_ID, &BTNInst); if(status != XST_SUCCESS) return XST_FAILURE; while(1); return 0;}

C Program (4C)

int IntcInitFunction(u16 DeviceId, XTmrCtr *TmrInstancePtr, XGpio *GpioInstancePtr){ XScuGic_Config *IntcConfig; int status;

// Interrupt controller initialization IntcConfig = XScuGic_LookupConfig(DeviceId); status = XScuGic_CfgInitialize(&INTCInst, IntcConfig, IntcConfig->CpuBaseAddress); if(status != XST_SUCCESS) return XST_FAILURE;

// Call to interrupt setup status = InterruptSystemSetup(&INTCInst); if(status != XST_SUCCESS) return XST_FAILURE;

C Program (5)

// Connect GPIO interrupt to handler status = XScuGic_Connect(&INTCInst, INTC_GPIO_INTERRUPT_ID,

(Xil_ExceptionHandler) BTN_Intr_Handler, (void *)GpioInstancePtr);


// Connect timer interrupt to handler status = XScuGic_Connect(&INTCInst, INTC_TMR_INTERRUPT_ID,

(Xil_ExceptionHandler)TMR_Intr_Handler, (void *)TmrInstancePtr);


C Program (6A)

// Enable GPIO interrupts interrupt XGpio_InterruptEnable(GpioInstancePtr, 1); XGpio_InterruptGlobalEnable(GpioInstancePtr);

// Enable GPIO and timer interrupts in the controller XScuGic_Enable(&INTCInst, INTC_GPIO_INTERRUPT_ID);

XScuGic_Enable(&INTCInst, INTC_TMR_INTERRUPT_ID);

return XST_SUCCESS;}

C Program (6B)

int InterruptSystemSetup(XScuGic *XScuGicInstancePtr){ // Enable interrupt XGpio_InterruptEnable(&BTNInst, BTN_INT); XGpio_InterruptGlobalEnable(&BTNInst);

Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT, (Xil_ExceptionHandler) XScuGic_InterruptHandler, XScuGicInstancePtr);

Xil_ExceptionEnable();

return XST_SUCCESS;

}

C Program (7)

Board Support Package

Hardware Platform Specification (1)



Documents

Interrupts AXI GPIO and AXI Timer ECE 699: Lecture 4