NU32v2: A Detailed Look at Programming the PIC32 - Revision history

Lynch at 11:17, 16 January 2016

2016-01-16T11:17:59Z

Lynch at 11:17, 16 January 2016

2016-01-16T11:17:05Z

Lynch at 11:16, 16 January 2016

2016-01-16T11:16:45Z

NickMarchuk: /* The PIC32 Bootloader and Bootloader App */

2011-02-14T23:20:55Z

The PIC32 Bootloader and Bootloader App

Lynch: /* The PIC32 Bootloader and Bootloader App */

2011-01-26T10:05:32Z

The PIC32 Bootloader and Bootloader App

Lynch: /* What Happens When the PIC Is Reset */

2011-01-26T10:01:55Z

What Happens When the PIC Is Reset

Lynch: /* What Happens When the PIC Is Reset */

2011-01-26T10:00:53Z

What Happens When the PIC Is Reset

Lynch: /* The PIC32 Virtual Memory Map */

2011-01-26T09:58:52Z

The PIC32 Virtual Memory Map

Lynch: /* The PIC32 Virtual Memory Map */

2011-01-26T09:58:35Z

The PIC32 Virtual Memory Map

Lynch: /* The PIC32 Virtual Memory Map */

2011-01-26T09:51:27Z

The PIC32 Virtual Memory Map

← Older revision		Revision as of 11:17, 16 January 2016
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	'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 BOARD. FOR INFORMATION ~~AND~~ SAMPLE CODE RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER," VISIT [[NU32\|THE NU32 PAGE]].'''		'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 PIC32 DEVELOPMENT BOARD. FOR INFORMATION, SAMPLE CODE, AND VIDEOS RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER," VISIT [[NU32\|THE NU32 PAGE]].'''

	After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.		After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.

← Older revision		Revision as of 11:17, 16 January 2016
Line 1:		Line 1:
	'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 BOARD. FOR INFORMATION AND SAMPLE CODE RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER, VISIT [[NU32\|THE NU32 PAGE]].'''		'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 BOARD. FOR INFORMATION AND SAMPLE CODE RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER," VISIT [[NU32\|THE NU32 PAGE]].'''

	After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.		After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.

← Older revision		Revision as of 11:16, 16 January 2016
Line 1:		Line 1:
			'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 BOARD. FOR INFORMATION AND SAMPLE CODE RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER, VISIT [[NU32\|THE NU32 PAGE]].'''

	After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.		After you have [[NU32v2: Starting a New Project and Putting it on the NU32v2\|programmed your PIC32 for the first time]] and verified that you can create a new project, compile it, and run it on your NU32v2, it is useful to take a step back and understand the basics of the programming process, beginning with a PIC32 fresh from the factory. We will do that on this page. We will begin by discussing the virtual memory map of the PIC32. To discuss the virtual memory map, it is useful to know ''hexadecimal'' (hex, or base 16) notation, where each digit of a hex number takes one of 16 values, 0...9, A...F. Since 16 = 2^4, a single hex digit represents four digits of a number written in binary (base 2). The table below gives examples.

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 * The NU32v2 bootloader project, written in MPLAB Assembly, with a "hello_world" type blinking LED example tacked on, is provided here: [[Media:NU32v2_pic32bootloader_source.zip|PIC32 code]].
-* The NU32v2_serial_bootloader app source code, written in Processing, is provided here: [[Media:NU32v2_serial_bootloader_source.zip|PIC32 code]].
+* The NU32v2_serial_bootloader app source code, written in Processing, is provided here: [[Media:NU32v2_serial_bootloader_source.zip|PIC32 code]]. '''New for Feb 14 2011- Should crash less. Email Nick if you repeatedly get Error # in the message area.'''
-* The Mac OSX executable version of the bootloader app is here: [[Media:NU32v2_serial_bootloader_osx.zip|NU32v2 serial bootloader for OSX]].
+* The Mac OSX executable version of the bootloader app is here: [[Media:NU32v2_serial_bootloader_osx.zip|NU32v2 serial bootloader for OSX]]. '''New for Feb 14 2011- Should crash less. Email Nick if you repeatedly get Error # in the message area.'''
 The NU32v2_serial_bootloader app allows the user to navigate to and select a .hex file.  No other file type selection is allowed.  The app also creates a button for each available serial COM port when the app loads, so the NU32v2 board must be powered up and the USB cable must be plugged in before the app is run.

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 The NU32v2_serial_bootloader app allows the user to navigate to and select a .hex file.  No other file type selection is allowed.  The app also creates a button for each available serial COM port when the app loads, so the NU32v2 board must be powered up and the USB cable must be plugged in before the app is run.
-'''Note about serial communication:'''  The NU32v2 board has an [http://www.ftdichip.com/Products/ICs/FT232R.htm FT232RL] built on to allow for easy communication over USB with your computer using an RS232 connection on the PIC32 end.  The communication is viewable as a "virtual com port" on your computer using the driver provided by FTDI.  This chip provides an easy way for your computer and the NU32v2 to communicate, for bootloading, debugging, and general communication.
+'''Note about serial communication:'''  The NU32v2 board has an [http://www.ftdichip.com/Products/ICs/FT232R.htm FT232RL] built on to allow for easy communication over USB with your computer.  This chip translates between the PIC's UART (RS-232) and your PC's USB protocol.  The communication is viewable as a "virtual com port" on your computer using the driver provided by FTDI.  This chip provides an easy way for your computer and the NU32v2 to communicate, for bootloading, debugging, and general communication.
 = Creating a .hex File Using MPLAB =

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 When the PIC is reset, it goes to the reset address 0xBFC00000, which is the location of the boot flash, and executes the code there.  The (assembly version of the) code that typically sits there, which is put there by a PIC programmer device, can be found in [[Media:NU32v2-crt0.S|pic32-libs/c/startup/crt0.S]].  This code takes care of some initialization tasks, then calls the code for the program you have written, which typically resides in the KSEG0 program flash memory block.
-With the NU32v2, we have a "bootloader" program that executes upon reset.  This program was placed in boot flash by a programmer.  More on the bootloader below.
+With the NU32v2, we have a "bootloader" program that executes upon reset.  This program was placed in the PIC's flash memory by a programmer device.  More on the bootloader below.
 <!--
 '''Give examples of what might be there, e.g., when programming with a programmer, or when the bootloader is on.'''  Say something about the crt0 code.  Defining _on_reset() to do anything time critical before crt0 finishes executing.  one function of crt0 is to fill statically allocated arrays with zeros in RAM, or to copy from flash to RAM any statically allocated initialized arrays.

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 = What Happens When the PIC Is Reset =
-When the PIC is reset, it goes to the reset address 0xBFC00000, which is the location of the boot flash, and executes the code there.  The (assembly) code that typically sits there, which is put there by a PIC programmer device, can be found in [[Media:NU32v2-crt0.S|pic32-libs/c/startup/crt0.S]].  This code takes care of some initialization tasks, then calls the code for the program you have written, which typically resides in the KSEG0 program flash memory block.
+When the PIC is reset, it goes to the reset address 0xBFC00000, which is the location of the boot flash, and executes the code there.  The (assembly version of the) code that typically sits there, which is put there by a PIC programmer device, can be found in [[Media:NU32v2-crt0.S|pic32-libs/c/startup/crt0.S]].  This code takes care of some initialization tasks, then calls the code for the program you have written, which typically resides in the KSEG0 program flash memory block.
 With the NU32v2, we have a "bootloader" program that executes upon reset.  This program was placed in boot flash by a programmer.  More on the bootloader below.

@@ Line 33: / Line 33: @@
 In addition to this virtual memory map, there is also a ''physical memory map''.  When you are writing a program, you only deal with the virtual memory map.  The PIC's CPU implements a Fixed Mapping Translation (FMT) unit that takes the virtual memory address and maps it to a physical memory address.  In other words, the virtual memory address is translated to a set of bit values on an addressing bus that allows the PIC's CPU to physically address the appropriate peripheral, flash memory location, RAM location, etc.  We will focus on the virtual memory map, not the physical memory map, since our goal is to program the PIC and we don't need to concern ourselves with how the FMT works.  If you're curious, however, the translation is a simple bitwise AND:
-physical address = virtual address & 0x1FFFFFFF
+      physical address = virtual address & 0x1FFFFFFF
 If you are directly accessing memory, independent of the CPU, as when an external device is engaged in direct memory access (DMA) with the PIC, you must use physical addresses. To learn more about physical addresses, see Section 3 of the PIC32 Family Reference Manual.

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 The PIC32 has a ''virtual memory map'' consisting of 4 GB (four gigabytes, or 2^32 bytes, where each byte equals 8 bits) of addressable memory.  All memory regions reside in this virtual memory space at their unique respective addresses.  This includes program memory (flash), data memory (RAM), peripheral special function registers (SFRs), etc.  For example, the peripheral SFRs begin at virtual memory location 0xBF800000 and end at virtual memory address 0xBF8FFFFF.  Subtracting the begin address from the end address, and adding one byte, we get 0x100000, which is 1*16^5 = 1,048,576 bytes, commonly written as 1 MB.  '''(Note:  Section 3 of the reference manual incorrectly indicates that the size of this region is 4 KB.)'''
-In addition to this virtual memory map, there is also a ''physical memory map''.  When you are writing a program, you only deal with the virtual memory map.  The PIC's CPU implements a Fixed Mapping Translation (FMT) unit that takes the virtual memory address and maps it to a physical memory address.  In other words, the virtual memory address is translated to a set of bit values on an addressing bus that allows the PIC's CPU to physically address the appropriate peripheral, flash memory location, RAM location, etc.  We will focus on the virtual memory map, not the physical memory map, since our goal is to program the PIC and we don't need to concern ourselves with the FMT.  (On the other hand, peripherals that access memory independently of the CPU, such as for DMA [direct memory access], must use physical addresses.  To learn more about physical addresses, see Section 3 of the PIC32 Family Reference Manual.)
+In addition to this virtual memory map, there is also a ''physical memory map''.  When you are writing a program, you only deal with the virtual memory map.  The PIC's CPU implements a Fixed Mapping Translation (FMT) unit that takes the virtual memory address and maps it to a physical memory address.  In other words, the virtual memory address is translated to a set of bit values on an addressing bus that allows the PIC's CPU to physically address the appropriate peripheral, flash memory location, RAM location, etc.  We will focus on the virtual memory map, not the physical memory map, since our goal is to program the PIC and we don't need to concern ourselves with how the FMT works.  If you're curious, however, the translation is a simple bitwise AND:
+physical address = virtual address & 0x1FFFFFFF
+If you are directly accessing memory, independent of the CPU, as when an external device is engaged in direct memory access (DMA) with the PIC, you must use physical addresses. To learn more about physical addresses, see Section 3 of the PIC32 Family Reference Manual.
 Virtual memory is partitioned into two types of address space:  ''user address space'' (the lower 2 GB) and ''kernel address space'' (the upper 2 GB).  By analogy to your personal computer, the kernel address space is to hold the computer's operating system, while the user address space is to hold a program that runs under the operating system.  This is for safety:  the user's program should not interfere with or compromise the operating system, e.g., it shouldn't be able to overwrite data that the operating system needs to function.  We will not be using an operating system, so our programs will reside in the kernel address space.