Getting the O in I/O to work on a typical microcontroller

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Cornelius West
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lines) on Blackfin chip (16) FLASH memory chip has additional I/O ports connected to Ez-Lite KIT LED s What do we need to have happen to make the FLASH memory work on a microcontroller as we want.

1 Getting the O in I/O to work on a typical microcontroller Ideas of how to send output signals to the radio controlled car. The theory behind the LED controller used in the Familiarization Lab Agenda Processors need to send out control signals (high / low 1 / 0 true / false) General Purpose Input / Output lines (GPIO lines) on Blackfin chip (16) FLASH memory chip has additional I/O ports connected to Ez-Lite KIT LED s What do we need to have happen to make the FLASH memory work on a microcontroller as we want. (In this example turning the board LED s on and off) What new Blackfin assembly language instructions do we need to learn in order to operate the LEDs? Blackfin BF533 I/O 2 Radio controlled car IN PRINCIPLE we could Connect the signal line that controls the LED1 output directly to the turn-to-right signal line of radio transmitter Connect the signal that controls the LED2 directly up to the go-forward signal line of radio transmitter Connect LED3 control to the turn-to-left signal line of radio transmitter IN PRINCIPLE means we might start off this way while we initially explore ideas to control the car. However we may (or may not) finish the project a different way. We WILL use LEDs as a VIRTUAL CAR CONTROLLER in Lab1 and 2. Meaning LED1 on means virtual car going forward etc Blackfin BF533 I/O 3 Programmable Flags (input Lab) Most micro-controllers have General Purpose Input or Output lines capable of generating true or false values Blackfin 533 has 16 GPIO lines Blackfin BF533 I/O 4

Where are the GPIO pins found on the board?

found on the Blackfin Evaluation Board. Video Control GPIO PF0 to PF7 Audio Control SPI interface (LAB.

line PF6 GPIO Pins are FUNCTIONALITY MULTIPLEXED pins can perform different functions at different times.

control LED on board Controlled using special additional parallel port interface attached to flash memory chip CAR CONTROL PROJECT LED

2 Where are the GPIO pins found on the board? (Shared with video PPI controller) GPIO lines are very useful They are used to sent control signals to many of the peripherals that are found on the Blackfin Evaluation Board. Video Control GPIO PF0 to PF7 Audio Control SPI interface (LAB. 4) Input -- Buttons GPIO PF8, 9, 10, 11 Output GPIO PF1, PF5, PF6, PF7 SPI interface LCD control line-- PF5 SPI interface Haptic Control line PF6 GPIO Pins are FUNCTIONALITY MULTIPLEXED pins can perform different functions at different times. (Same on ARM boards used in MPG) Blackfin BF533 I/O 5 Blackfin BF533 I/O 6 Additional I/O pins available Blackfin BF533 I/O 7 Used to control LED on board Controlled using special additional parallel port interface attached to flash memory chip CAR CONTROL PROJECT LED configuration LEDs used to INDICATE direction radio-controlled car will move. Not currently used to control the car (but could be done if needed a quick fix ). VIRTUAL CAR INTERFACE BACK / DONE LED 4 LEFT -- LED 3 FORWARD LED 2 BACK LED 1 CONTROL TURN CAR POWER SUPPLY ON LED 5 Blackfin BF533 I/O 8

BLACKFIN FLASH MEMORY UNIT Major task of this unit is to store the code need to boot (start) the processor 2 PSD4256G6V From STMicroElectronics The FLASH part we need during Lab.

CHANGE PB6_A, PB7_A BEHAVIOUR WHEN YOU CODE THE LED OPERATION (Remember ROW and RAW Use AND / OR instructions) Airplane falls from sky syndrome Blackfin BF533 I/O 10 4 Steps to activating LEDs 1.

3 BLACKFIN FLASH MEMORY UNIT Major task of this unit is to store the code need to boot (start) the processor 2 PSD4256G6V From STMicroElectronics The FLASH part we need during Lab. 1 Additional I/O pins 8 ports of 8 GPIO pins Blackfin BF533 I/O 9 LEDs connected to FLASH port LEFT FORWARD RIGHT BACK / DONE CAR POWER These pins are controlling other things on the board DON T CHANGE PB6_A, PB7_A BEHAVIOUR WHEN YOU CODE THE LED OPERATION (Remember ROW and RAW Use AND / OR instructions) Airplane falls from sky syndrome Blackfin BF533 I/O 10 4 Steps to activating LEDs 1. Get the FLASH memory to work correctly (set many FLASH registers) Write the code for InitFlashASM( ) 2. Get the FLASH I/O Port to work correctly as output for pins PB5 PB0, leaving other pins unchanged Write the code for InitFlashPortASM( ) 3. Write the value we want to LEDs WriteFlashLEDASM( int value) 4. Read back the value the LEDs show int ReadFlashLEDASM( ) for testing Blackfin BF533 I/O 11 BF533 FLASH MEMORY UNIT Controlled through EBIU External Bus Interface Unit EBIU are common on most processors (although often by different name) ASK ME ABOUT WAIL_INT and JIT_Knowledge FLASH OTHER PINS USED FOR SPECIAL CONTROL PURPOSES WAIL_INT! SDRAM CONTROLLER Blackfin BF533 I/O 12

Key information about EBIU Three busses come into the EBIU from the Blackfin processor core Forwards data to SDRAM and FLASH How does EBIUineterface logic KNOW whether which data values have to be

4 Key information about EBIU Three busses come into the EBIU from the Blackfin processor core Forwards data to SDRAM and FLASH How does EBIUineterface logic KNOW whether which data values have to be send to FLASH unit (I/O) and which data values to the SDRAM units (memory store)????? (Control logic question on quiz / exams) SDRAM and FLASH In later laboratories We will build a stand-alone microcontroller system, which means we will need to understand how to program the flash memory so that the processor knows what to do when powered-up. Common practice on processors for the boot process to read start up code from FLASH We will need to process large data arrays too large to fit into the internal fast Blackfin L1 memory so they must be placed in SDRAM. Common practice on processors E-UNIT run out of memory problems In this laboratory, we need to program the extra FLASH chip I/O pins which are connected to the LED s control the lights now (virtual car video display), perhaps used to control real car later. Blackfin BF533 I/O 13 Blackfin BF533 I/O 14 What we (should) already know must happen! When the processor powers up it must read its boot program from the FLASH memory. See micro-controller lecture The processor does not know what sort of FLASH it will be connected to When processor powers up, it will assume that it is connected to slowest FLASH in existence. (common practice) The first part of the program the processor reads in (boot code) will change the processor memory control logic to read FLASH more efficiently (faster). Blackfin BF533 I/O 15 Controlling FLASH operation The EBIU control registers we need to worry about in Lab. 1 Blackfin EBIU (like most microcontroller peripherals) has a GLOBAL control register and one or more specific control registers COFFEEPOT and SPI interfaces have only 1 control register Blackfin BF533 I/O 16

Init_LED_GPIOInterface( ) -- Run once code Get the FLASH memory to work correctly Careful -- May be many processes (threads) running on the Blackfin evaluation board (e.g. Audio).

$MANUAL Init_LED_GPIOInterface( ) { /* Concept only */ If FLASH memory already configured return without changing those other initializatiosn -- How can we know if already configured?$ -- Perhaps something changed during other initialization! Else { Configure Memory Bank control register for Lab.

-- Perhaps something changed during other initialization! Else { Configure Memory Bank control register for Lab.

and write operation) Blackfin BF533 I/O 18 Memory control access speed (default slow) Diagram often appears in quiz DEFAULT (Power up) Processor sends out address and waits 15 cycles before sending a

5 Init_LED_GPIOInterface( ) -- Run once code Get the FLASH memory to work correctly Careful -- May be many processes (threads) running on the Blackfin evaluation board (e.g. Audio). All these processes (threads) may want to use the flash memory for other purposes meaning InitFlashCPP( ) may have already been called by another thread before your code uses it (or perhaps your code is run more than once) Set the Bank control register Reset value the way the processor powers up Will probably work as is but not efficient slow reads by default (common practice for hardware) FROM MANUAL Init_LED_GPIOInterface( ) { /* Concept only */ If FLASH memory already configured return without changing those other initializatiosn -- How can we know if already configured? -- Perhaps something changed during other initialization! Else { Configure Memory Bank control register for Lab. 1 THEN configure the Global control registers (turns on the FLASH) } This is an example of design using pseudo code } Blackfin BF533 I/O 17 Default Control Configuration Slow (15 cycles for each read and write operation) Blackfin BF533 I/O 18 Memory control access speed (default slow) Diagram often appears in quiz DEFAULT (Power up) Processor sends out address and waits 15 cycles before sending a do a read operation command to memory. The processor waits another 15 cycles before the actual read occurs. Blackfin BF533 I/O 19 Set General Control Register Reset value (Processor power up state) leaves CLKOUT disabled is that important? (Meaning do WE have to turn peripheral on (set bit 0) to 1)?) RAW and ROW What parts of the register (which bits) register must we know Unanswered at this time. We don t know what bits are critical NOT to change. SO CHANGE USING AND and OR instructions when setting All Banks enabled Blackfin BF533 I/O 20

6 Init_LED_GPIOInterface( ) InitFlashPortCPP( ) Get the Port to work correctly as output for pins PB5 PB0, leaving other pins unchanged. (Set as Output to control the lights) Get the Port to work correctly as output for pins PB5 PB0, leaving other pin behaviour (6 and 7) unchanged. (Use AND and OR instructions) C++ and ASM WARNING These are BYTE registers -- HDWK Documentation says the Flash Direction register allows you to choose whether the pin works as an in pin or works as an out pin (common practice) ASK ME ABOUT THE IMPORTANCE OF -- HDWK CHANGE INTERFACING FROM ASM TO CPP CODE WARNING STARTS AT 0 BOTH BIT AND LED NAMES Name of OUR part BITS LED 5 Leftmost on Blackfin panel LED 4 LED 3 LED 2 LED 1 LED0 Rightmost Used during Write and Read operations Write 1 to a bit -- turn on Write 0 to a bit -- turn off All informa from th evaluat kit hardwa manua Blackfin BF533 I/O 21 Blackfin BF533 I/O 22 Key issues -- Init_LED_GPIOInterface() FUNCTION MUST DO -- Set direction to 1 (output) on lower 6 pins connected to LEDs, leaving other direction values unchanged NEED TO REVIEW ENCM369 OR assembly code instruction needed 8 bit values (byte) READ, USE OR, WRITE (ROW) Direction registers common on most I/O peripherals (devices) Read EBIU direction register into processor core data register (makes a copy) (HOW?) Set another processor data register to 0x3F (b ). Need to know basic binary and hexadecimal patterns for common numbers decimal confusing when used to show on and off values no calculators allowed in exams and quizzes Perform OR operation on the two data registers (HOW?) Write modified copy back into direction register (HOW?) PROBLEM to solve How do we do byte read and writes to Blackfin memory using C++ and do OR s? Blackfin BF533 I/O 23 CHANGE INTERFACING FROM ASM TO CPP CODE Write_LED_GPIOInterface( ) FUNCTION MUST DO -- Write 1 (on) or 0 (off) to the Port to activate LEDs connected to pins PB5 PB0, leaving other pins on that port unchanged in value. (common practice) BITS LED 5 Leftmost LED 4 LED 3 LED 2 LED 1 LED0 ROW and RAW needed CHANGE INTERFACING FROM ASM TO CPP CODE Blackfin BF533 I/O 24

7 Key issues Write_LED_GPIOInterface( input_value) FUNCTION MUST DO -- Write 1 (on) or 0 (off) to the Port to activate LEDs connected to pins PB5 PB0, leaving other pins unchanged. HOW TO DO THIS OPERATION 1. Read 8-bit BYTE LED data register into 32-bit processor data register (makes a copy in R1) 2. Keep top 2 bits (AND operation) of copied value (8 bit) in 32-bit register 3. Keep bottom 6 bits of in-par 32-bit in_value (R0) that is passed into the subroutine 4. OR operation on two processor data registers (R0, R1) 5. Write modified 32-bit copy back into LED data register 8-bit byte operation needed PROBLEM TO SOLVE : How to do byte (8) operations using word (32) sized register operations (Use all, rather than some, register bits often easier) EXAMPLE NOT YET BEING DONE IN HIGH LEVEL C++ Oips Blackfin BF533 I/O 25 PPP: We have reduced the number of things we STILL need to learn how to do How do we put a 32-bit value (long int) into a register (data Rn or pointer Pn)? How do we put an 8 or 32-bit value into memory? How do we handle byte operations (8-bit)? How do we do AND and OR operations on Blackfin? Do these both in ASM and CPP? How similar is Blackfin to MIPS when handling these issues (ENCM369)? Meaning can we use ENCM369 ideas with the Blackfin? (Can we remember how to do the equivalent operations on MIPS?) Blackfin BF533 I/O 26 Agenda tackled Processors need to send out control signals General purpose input / output GPIO on processor Not enough GPIO lines FLASH memory chip has additional I/O ports connected to Ez-Lite KIT LED s What do we need to have happen to make the FLASH memory work as we want? What new Blackfin assembly language instructions do we need to learn? Blackfin BF533 I/O 27

Getting the O in I/O to work on a typical microcontroller

Getting the O in I/O to work on a typical microcontroller Ideas of how to send output signals to the radio controlled car. The theory behind the LED controller used in the Familiarization Lab Agenda Processors