-----Original
Message-----
From: Michael
To: Shane Tolmie
Subject:
bootloader
Shane - I just gave the latest version (5.10) a shot (along
with Petr Kolomaznik's downloader), and it works beautifully.
I had been trying to figure out how to get Rick Farmer's
PICLOADER to work with my application, but had been coming
up blank - your bootloader is absolutely painless, and I
don't have to modify my code at all!!
Thanks a lot! - Michael
1.
First, connect the serial port of your computer to the PIC micro. The
serial port operates at +/- 13V, and the PIC serial operates at +5V/0V. Use
a MAX232, MAX3222, or SIPEX232 level shifter to connect the serial port of
the computer to pins RX/TX on PIC. For the schematic, see the .gif and Protel
99 .sch files in the distributon download.
You only need one serial port - ignore the M2_xx lines in the schematic as
they are not needed for a simple bootloader.
The FAQ at http://www.microchipc.com/ has the same schematic diagrams, plus
a troubleshooter guide for non-working serial ports.
2. Select the correct .hex file. You must get
the crystal speed correct. Options are 3.6864, 4, 16 and 20Mhz for the 16F873
or 16F876. As far as programming goes, its only based on memory size, so the
2k 16F870/1/2 are the same, the 4k 16F873/4 are the same, and the 8k 16F876/7
are the same. For example, a 16F876, 16Mhz, downloading at 19200 baud would
be "61619 - bootldr-v2-16F876-77-16Mhz-19200bps.hex".
3.Recompile
your code so it doesnt overwrite the bootloader. This will not normally be
necessary, unless your program occupies a lot of memory.
The bootloader uses 256 instructions at the top of flash.
16F876/7, which has 8k of ROM, this is flash locations 0x1F00 to 0x1FFF.
16F873/4, which has 4k of ROM, this is flash
locations 0x0F00 to 0x0FFF.
16F870/1, which has 2k of ROM, this is flash
locations 0x0700 to 0x07FF.
Hi-Tech C v8-00 and
above, for 8k parts such as the 16F876 or 16F877 add -RESROM1F00-1FFF.
This method is recommended
over adding the -ICD switch.
Hi-Tech C v7.83 or
below: add -ICD to the PICC
options. This reserves the top 256 bytes of the ROM for the ICD (In-Circuit-Debugger),
which means the bootloader also fits in.
CCS C: add *only one*
of the next two statements, depending on the micro:
#ORG 0x0700,0x07FF {} //for the 2k 16F870/1/2
#ORG 0x0F00,0x0FFF {} //for the 4k 16F873/4
#ORG 0x1F00,0x1FFF {} //for the 8k 16F876/7
For some versions of CCS C, use the following:
#org 0x0700, 0x07FF
void loader16F872(void) {} //for the 2k 16F870/1/2
#org 0x0F00, 0x0FFF void loader16F874(void) {} //for the 4k 16F873/4
#org 0x1F00, 0x1FFF void loader16F877(void) {} //for the 8k 16F876/7
Assembly: add an equivalent
line reserving these program locations.
Pascal: its definitely
possible. Contact me if you have any problems.
4.
This section only applies to bootloader v6-52 and below.
The goto instruction after RESET (address 0x0000-0x0003) is usually a long
jump, not a short jump, in 99% of cases. If the bootloader doesnt work, check
this out.
The first 4 bytes in the .hex file should be a long jump. (this is
true for most .hex files including Hi-Tech C and CCS C). It is known that
the CC5X compiler, a Pascal compiler and various assembly language programs
do not have this long jump.
If the .hex file has a short jump, ie: goto start, it wont work. The first
4 bytes should have instructions similar to the instructions below:
ORG 0x0000 ;reset vector
clrf 0x3 ;zero status
movlw 0x00 ;high byte of long jump <<<these next 2 lines are important
movwf 0xA ;zero PCLATH
goto start ;ie: if 'start' offset=0xFD, execute long jump to 0x00FD
;bootloader executes these 4 instructions to jump from top of memory, at address
0x1F00, back to program entry point
5. Program the target pic micro with this
.hex file with a programmer such as the ICD2 (search for "ICD2" from www.microchipc.com). Third party programmers are discussed at http://www.micahcarrick.com/v2/content/category/4/2/8/
6. Run "pic_downloader.exe". Choose 19200bps,
write eeprom, and the .hex file to download.
To test that the bootloader is working, use the supplied test files. All they
do is write serial characters out of the serial port. For example, for a 16Mhz
crystal, choose "_19160 - test_serial_19200baud_16Mhz.hex".
7. Click "Write" within the windows
application software. It should display the message "Searching for bootloader
..."
8.
Reset PIC micro now, and the writing will begin.
9. The test program simply prints out a single
text message @ 19200 baud on powerup. Run '19200-com1.ht' to see the output,
this is a HypterTerminal file with settings of 19200,N,8,1,flow control:none.
10.In future, after powerup, bootloader
times out in 200ms and then runs the target program normally.
Compatibility
list
Note: for the benefit of other users, if you find an addition
to this list, please email support@microchipc.comso I can update this list. Your email may save lots of users a lot of time,
as it allows me to fix the bootloader. Thanks!
v7-30 has been
tested:
16F876 and 16F877,
4Mhz, 10Mhz and 16Mhz for both.
Small programs (200
word) and large programs (1 word short of writing over the bootloader).
With the MPLab-ICD
used as a substitute programmer. The assembly language source must be recompiled.
I am currently working
on a version of the bootloader which works with the CC5X compiler - email
me if you want a quick fix.
v6-52 of bootloader
has been tested with with Hi-Tech C and CCS C compiler, and assembly language
programs with a long jump. It does *not* work with PicBasic.
This version of the compiler
is known to have issues with the CC5X compiler, and Pascal compiler. These
both work if a long jump is inserted into the first 4 bytes (see troubleshooting).
Troubleshooting
step-by-step
Q.
Nothing works - where do I start?
You need a chip programmer
to get the bootloader .hex file into the PIC micro in the first place.
It is only after the bootloader has been programmed into the PIC micro
that new programs can be loaded into the micro using only the RS232
serial port on a PC. The top 4 programmers available are:
Next, check that
your circuit is correct. For PIC16F87x, 19200bps, 4Mhz, use "test_serial_19200bps_4Mhz.hex".
Program your PIC with the .hex file, and using HyperTerminal set to
19200bps, N,8,1, no hardware flow control, check that it is outputting
serial characters. It should repeatedly output a string: [alive].
The bootloader
has been changed to work with the 16F87xA.
A MAX232
needs at least 1.0uF capacitors, different from the MAX232A which
only needs 0.1uF capacitors.
A MAX233
doesnt need any capacitors.
The bootloader
does not work with the 16F872 as it doesnt have a UART.
Q.
I want to use the MPLab-ICD with the bootloader
Yes, this works nicely.
However, first you
must re-assemble the included .asm file.
The MPLab-ICD uses the top 256 bytes of memory on the 16F876 for its
own purposes.
Normally, the bootloader
uses the top 256 instructions in memory. So, move the bootloader down
256 instructions to sit below the MPLab-ICD reserved memory, by re-assembling
it.
In the supplied
.zip file, in the directory 'assembly source', open up bootldr.asm.
Change the #define ICD_DEBUG 0 to #define ICD_DEBUG 1.
Check crystal speed, and re-assemble.
After this, you
must reserve the top 512 instructions in your application for
the bootloader/MPLab-ICD combination.
For example, for
Hi-Tech C v8-00 and above, with 8k parts such as the 16F876 or 16F877,
add the command line option -ICD for the ICD. This reserves the top
256 instructions, and some ram (0x70 and more) for the ICD. In addition,
add -RESROM1E00-1EFF
to reserve 256 instructions below the ICD memory for the bootloader.
Do not combine these two command line calls into -RESROM1E00-1FFF
as this doesnt reserve the ram needed for the ICD.
Now, remember to
have enable debug mode set to 'off', see the screenshot here.
Program the bootloader .hex file into the 16F876 with the MPLab-ICD,
then try it out.
Q.
Is your compiler compatible with the bootloader?
Hi-Tech C
is compatible. Reserve
top 256 of memory locations for bootloader.
Heres how.
CCS C is
compatible.
For v2.xxx, simply reserve top 256 of memory locations for bootloader.
Heres how.
Assembly language is compatible, with possible modifications.
Check conditions.
PicBasic
is compatible,
with modifications. Heres how.
CC5X
compiler is compatible, with modifications. Heres
how.
All others compiler / assemblers. Check
conditions for correct operation.
Q.
Can I run the bootloader with WDT enabled?
Yes. For modifications, see instructions in the distribution download.
Q
Why does my circuit keep resetting? Or not start up at all?
By default, if you have Low Voltage Programming (LVP) enabled, touching
pin RB4 will reset the micro. In the worst case, a bad logic level on
RB4 will keep the micro in reset.
Troubleshooter
is Finished
Answers to Troubleshooting Questions
Q.
Have you reserved space for bootloader?
The bootloader needs the
top 256 bytes of memory for itself. Add instructions to reserve
these memory locations.
For a 4k
16F873 or 16F874, this is memory locations 0xF00 to 0xFFF.
For an 8k
16F876 or 16F877, this is memory locations 0x1F00 to 0x1FFF.
For
the Hi-Tech C compiler, the -ICD
compiler switch reserves the top 256 instructions for the In-Circuit
Debugger. Add this switch to the compiler options in project setup to
reserve space for the bootloader.
For CCS C, add one of the following
lines:
#org 0x0700, 0x07FF
void loader16F872(void) {} //protect
bootloader code for
the 2k 16F870/1/2
#org 0x0F00, 0x0FFF void loader16F873(void) {} //protect
bootloader code for
the 4k 16F873/4
#org 0x1F00, 0x1FFF void loader16F876(void) {} //protect
bootloader code for
the 8k 16F876/7
For PicBasic:
yet to be advised - email me
if you know!
The CC5X
needs a modification to the source code. See the complete solution.
For Assembly
language: add an equivalent line reserving these program locations.
A.
How to make the CC5X compiler work with the bootloader
If you have CC5X v2.74, then perform step 1 only - the bootloader
just needs the top 256 bytes of memory reserved for the bootloader.
If you have CC5X
v3.1, then perform steps 1 and 2 - the reset jump must also
be altered to clear PCLATH on startup.
These statements
have to be entered in the beginning of the C program:
Reserve the top
256 instructions for the bootloader. These statements can be
placed in user program, but should replace the original statements
in the header files for these processors, 16F877.h and 16F873.h.
For a PIC16F876 or PIC16F877 with 8k of FLASH:
#pragma chip PIC16F873, core
14, code 0x1F00, ram 32 : 0xFF /0 /3 //set top address to protect
bootloader code
For a PIC16F873
or PIC16F874 with 4k of FLASH:
#pragma chip PIC16F873,
core 14, code 0x0F00, ram 32 : 0xFF //set top address to protect
bootloader code
Manually set
the PCLATH register and add a few NOP instructions.
#pragma cdata[0] = 0x0180 + 0x0A // CLRF PCLATH, prepare for code
page change
#pragma cdata[1]
= 0 // NOP
#pragma cdata[2] = 0 // NOP
#pragma resetVector 3 // start address for user program
This setting also
works with interrupt function which will be placed with starting address
0x04.
CC5x v3.1 have these
commands, this is not tested with older versions of CC5x.
- Many grateful thanks to Tore Bergvill from Oslo, Norway and Pierre
Brochard, Paris.
Q.
What conditions are necessary for a generic assembler / compiler to
work with the bootloader?
Check
that the top 256 instructions of flash are reserved. Heres
how.
If your compiler
/ assembler is on the compatibility list, modify it as per instructions.
Heres how.
If this fails, the
first 4 bytes in the .hex file should be a long jump. This is
fairly standard - most compilers have this by default.
However, for some assembler programs or Pascal compilers, there may
be a short jump, without a PCLATH=0
instruction. This won't work in some circumstances (eg: the CC5X compiler
needs changes - see here).
If you're programming in assembler, match the first 4 lines of your
program to that below.
Heres an example of the first 4 instructions that the Hi-Tech C compiler
uses. This works perfectly.
ORG 0x0000 ;reset vector
clrf 0x3 ;zero status
movlw 0x00 ;high byte of long jump
movwf 0xA ;zero PCLATH
goto start ;ie: if 'start' offset=0xFD, execute long jump to 0x00FD
;bootloader executes these 4 instructions to jump from top of memory,
back to program entry point
;reset vector is at ORG 0x0004, from here on.
Top.
Q.
What about PICBasic?
The latest version
of the bootloader works perfectly with
PicBasic.
PicBasic v2.33
- First line in the program should be DEFINE LOADER_USED 1. This command
tells the compiler to start at location 0x004.
PicBasic v2.31
and 2.32 - First line in the program should be DEFINE ONINT_USED 1
Note: If PBpro interrupts
are used, there is no need for either of these defines.
Q.
Can I run the bootloader with WDT enabled?
Yes. Here is an email I received from a user ...
"Hello Shane,
I was download
your PIC bootloader archive v8.01 and try it with
some of my HiTech PICC code. In my code watchdog must be enabled and
when I download it to PIC it does not work even if I enable WDT when
programming PIC. So, I look in your asm code of bootloader and found
this piece of code:
Main
btfss STATUS,NOT_TO ;run user program after WatchDog-TimeOut
goto UserStart
start
movlw 0x90
.
In PIC16F87x
datasheet I found this table:
STATUS BITS AND THEIR
SIGNIFICANCE
----------------------------------
POR BOR TO PD
0 x 1 1 Power-on Reset
0 x 0 x Illegal, TO is set on POR
0 x x 0 Illegal, PD is set on POR
1 0 1 1 Brown-out Reset
1 1 0 1 WDT Reset
1 1 0 0 WDT Wake-up
1 1 u u MCLR Reset during normal operation
1 1 1 0 MCLR Reset during SLEEP or interrupt wake-up from SLEEP
so I notice that
the above code must be changed for proper operation
with WDT enabled:
Main
btfsc STATUS,NOT_TO ; run user program after WatchDog-TimeOut
goto start
clrwdt
goto UserStart
start
movlw 0x90.
Now, with this code
I can test programs with or with out WDT enabled
and used.
I hope you understand
my English and what I want to say.
[Thanks for this
info! - Ed.]
--
sincerely,
Branko
branek@eunet.yu
http://solair.eunet.yu/~branek
ICQ: 15616778
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New in v7.60, the bootloader works with both low voltage and normal
5V chips.