EECS 192: Mechatronics Design Lab Discussion 11: Embedded Software - - PowerPoint PPT Presentation

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Sep 28, 2023 148 likes •395 views

EECS 192: Mechatronics Design Lab Discussion 11: Embedded Software GSI: Varun Tolani 4 & 5 April 2018 (Week 11) 1 Intro 2 Timers 3 Communication & UART 4 Structuring Your Code Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April

SLIDE 1

EECS 192: Mechatronics Design Lab

Discussion 11: Embedded Software GSI: Varun Tolani 4 & 5 April 2018 (Week 11)

1 Intro 2 Timers 3 Communication & UART 4 Structuring Your Code

Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 1 / 24

SLIDE 2

Intro Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 2 / 24

SLIDE 3

Intro

What does all this mean?

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SLIDE 4

Intro Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 4 / 24

SLIDE 5

Timers

Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 5 / 24

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Timers

What are some of the different kinds of timers?

◮ Periodic Interrupt Timer (PIT) ◮ Flexible Timer Module (FTM) ◮ Programmable Delay Block (PDB) ◮ Real Time Clock (RTC)

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SLIDE 7

Timers

When do we use these timers?

◮ Periodic Interrupt Timer (PIT)

◮ Running functions periodically (i.e. control)

◮ Flexible Timer Module (FTM)

◮ Running functions periodically (i.e. control) ◮ Generating PWM

◮ Programmable Delay Block (PDB)

◮ Delaying for a specific amount of time

◮ Real Time Clock (RTC)

◮ Tracking execution time (i.e. get curr time) Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 7 / 24

SLIDE 8

Timers

PIT (Review)

#define PIT_IRQ_ID PIT0_IRQn #define PIT_SOURCE_CLOCK CLOCK_GetFreq ( kCLOCK_BusClk ) // config -> enableRunInDebug = false; PIT_GetDefaultConfig (& pitConfig); PIT_Init(PIT , &pitConfig); /* Set timer period for channel 0 */ PIT_SetTimerPeriod (PIT , kPIT_Chnl_0 , USEC_TO_COUNT (500000U, PIT_SOURCE_CLOCK )); // .5s timing /* Enable timer interrupts for channel 0 */ PIT_EnableInterrupts (PIT , kPIT_Chnl_0 , kPIT_TimerInterruptEnable ); /* Enable at the NVIC */ EnableIRQ( PIT_IRQ_ID ); PIT_StartTimer (PIT , kPIT_Chnl_0 ); Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 8 / 24

SLIDE 9

Timers

FTM as a timer (prescaler)

#define BOARD_FTM_BASEADDR FTM0 #define BOARD_FTM_IRQ_NUM FTM0_IRQn #define BOARD_FTM_HANDLER FTM0_IRQHandler #define FTM_SOURCE_CLOCK ( CLOCK_GetFreq ( kCLOCK_BusClk )/4) FTM_GetDefaultConfig (& ftmInfo); ftmInfo.prescale = kFTM_Prescale_Divide_4 ; /* Initialize FTM module */ FTM_Init(BOARD_FTM_BASEADDR , &ftmInfo); FTM_SetTimerPeriod (BOARD_FTM_BASEADDR , USEC_TO_COUNT (1000U, FTM_SOURCE_CLOCK )); // Enable Interrupts FTM_EnableInterrupts (BOARD_FTM_BASEADDR , kFTM_TimeOverflowInterruptEnable ); EnableIRQ( BOARD_FTM_IRQ_NUM ); FTM_StartTimer (BOARD_FTM_BASEADDR , kFTM_SystemClock ); Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 9 / 24

SLIDE 10

Timers

FTM

◮ There are 4 FTM’s’s (0-3) ◮ Each FTM has up to 8 channels (think h bridge or even brushless

motor control)

◮ Each FTM runs is locked to 1 frequency (but not duty cycle!!!) ◮ FTM allows you to use a prescaler (to count very slowly without

verflow)

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SLIDE 11

Timers

FTM for PWM (review)

#define BOARD_FTM_BASEADDR FTM0 #define BOARD_FTM_IRQ_NUM FTM0_IRQn #define BOARD_FTM_HANDLER FTM0_IRQHandler #define FTM_SOURCE_CLOCK kCLOCK_BusClk

ftmParam. chnlNumber = BOARD_FTM_CHANNEL ;

ftmParam.level = PWM_LEVEL;

ftmParam. dutyCyclePercent = init_duty_cycle ;
ftmParam. firstEdgeDelayPercent = 0U;

FTM_GetDefaultConfig (& ftmInfo); ftmInfo.prescale = kFTM_Prescale_Divide_128 ; // Optional for slow PWM FTM_Init(BOARD_FTM_BASEADDR , &ftmInfo); // Dont Need Interrupts Here !!! FTM_SetupPwm (BOARD_FTM_BASEADDR , &ftmParam , 1U, kFTM_CenterAlignedPwm , freq_hz , FTM_SOURCE_CLOCK ); FTM_StartTimer (BOARD_FTM_BASEADDR , kFTM_SystemClock ); Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 11 / 24

SLIDE 12

Communication & UART

Communication and UART

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Communication & UART UART

Universal Asynchronous Reciever and Transmitter

◮ Asynchronous Digital Data Transfer Protocol ◮ Data format and Data speed (baud rate) are configurable ◮ Used for serial communication (USB, ethernet, etc.) ◮ Transmits data as byte string ◮ User chosen baud rate (bits/second)

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SLIDE 14

Communication & UART UART

UART

Tx- Transmit, Rx- Receive, G- Gnd (only need 3 pins for UART data transmission)

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SLIDE 15

Communication & UART UART

Baud Rate

Baud = bits/second Some common baud rates are 9600, 38400, 115200

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SLIDE 16

Communication & UART UART

Bluetooth on K64F

We can just plug in our bluesmirf chip directly to the K64F!

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Communication & UART Telemetry

Telemetry

◮ Why Telemetry

◮ Necessary for checkpoint 9 and race 1/2 ◮ Invaluable for real time debugging

◮ Telemetry uses UART!

◮ Can do asynchronous communication ◮ Floating Point! ◮ Easy to switch between USB & Bluetooth Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 17 / 24

SLIDE 18

Communication & UART Telemetry

Our Telemetry System

telemetry uart.c (in telemetry skeleton code)

#define DEMO_UART UART0 #define DEMO_UART_CLKSRC UART0_CLK_SRC #define DEMO_UART_CLK_FREQ CLOCK_GetFreq ( UART0_CLK_SRC ) #define DEMO_UART_IRQn UART0_RX_TX_IRQn #define DEMO_UART_IRQHandler UART0_RX_TX_IRQHandler void init_uart(void){ uart_config_t config; /* * config. baudRate_Bps = 115200U; * config. parityMode = kUART_ParityDisabled ; * config. stopBitCount = kUART_OneStopBit ; * config. txFifoWatermark = 0; * config. rxFifoWatermark = 1; * config.enableTx = false; * config.enableRx = false; */ UART_GetDefaultConfig (& config);

config. baudRate_Bps = 115200U;

config.enableTx = true; config.enableRx = true; UART_Init(DEMO_UART , &config , DEMO_UART_CLK_FREQ ); }

UART0 routes to USB if plugged in! For bluetooth need to use UART corresponding to PTC14/15

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SLIDE 19

Communication & UART Telemetry

Our Telemetry System (as of April 3)

Data flows 1 way

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SLIDE 20

Communication & UART Telemetry

Tips for Telemetry

◮ Get telemetry working via usb first ◮ Use the same baud rate on your laptop, K64, and bluetooth chip (will

not work if you ignore this)

◮ The bluetooth chips come preconfigured from previous years to run at

a certain baud rate (usually 9600, 38400, or 115200). You can change this if needed.

◮ Using telemetry with a slower baud rate is recommended (9600 or

38400).

◮ Logging too many variables (especially waterfall plots) will slow down

your cpu.

◮ Known Telemetry Issues

◮ Can only transfer 32bit values as of now ◮ Data only flows 1 direction ◮ Blocking writes used Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 20 / 24

SLIDE 21

Structuring Your Code

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SLIDE 22

Structuring Your Code

Code Structure 1

Closed Loop Control & Telemetry

int main (){ init_pit(freq , pit_handler ); while (1){ telemetry.do_io (); } } void pit_handler (){ estimate_velocity (); find_line (); calculate_steering_error (); calculate_velocity_error (); apply_steering_control (); apply_velocity_control (); } Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 22 / 24

SLIDE 23

Structuring Your Code

Code Structure 2

Closed Loop Control & Telemetry

int main (){ init_pit(freq , pit_handler ); while (1){ PRINTF(’debugging\r\n’); telemetry.do_io (); } } void pit_handler (){ estimate_velocity (); find_line (); calculate_steering_error (); calculate_velocity_error (); apply_steering_control (); apply_velocity_control (); }

Why might this be a bad idea?

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SLIDE 24

Structuring Your Code

Code Structure 3

Closed Loop Control & Telemetry

int main (){ init_pit(freq , pit_handler ); init_idle_task (); while (1){ SPRINTF(’debugging\r\n’); telemetry.do_io (); } } void idle_task (){ PRINTF(queue.pop ()); } void pit_handler (){ estimate_velocity (); find_line (); calculate_steering_error (); calculate_velocity_error (); apply_steering_control (); apply_velocity_control (); } Ducky (UCB EECS) Mechatronics Design Lab 4 & 5 April 2018 (Week 11) 24 / 24