Why use a bootloader?

[Fredrick]

What´s the point as a hobby PIC programmer to use a bootloader if you have a programmer?

You can program the PIC witout a programmer but you still need a USB/Serial interface to a PC, right?

[aratti]

Sometimes you need to update the software on chips soldered to the PCB. Without a bootloader, this could be a real problem.

If you can remove the pic from the circuit, well you can do it with the programmer, But with the bootloader you don't need to remove the chip and this is an additional plus.

Al.

[Fredrick]

You could use ICSP if you want to update the software on a PIC on a PCB

[tenaja]

First, bootloaders are faster than a programmer. Second, ICSP takes up more pins (3), and limits the hardware to the pins. A bootloader only takes two serial pins, and if you already have a serial connection, requires no special treatment. Third, if you have the board in an enclosure, it is safer to have a serial connection to the outside world than your mclr pin.

In reality, from a hobbyist standpoint, it doesn't make a big difference. It is convenient, however.

[Jumper]

Because a bootloader will save tons of money when then enduser can correct the major bugs in the software just by using a serial cable and downloading the patch from internet :-)

In true errata Microchip style...

[Ioannis]

Note that a bootloader (normaly) cannot lock your code on the PIC. So for commercial usage this is a minus.

Ioannis

[Jumper]

Any bootloader can program the pic even if code protection is turned on... it is just access to the code area with a programmer that code protection protects from. Not from inside the PIC.

BUT since you download the HEX file from internet it better be a loader with encryption or the code is public anyway :-)

[Fredrick]

Ok..

Where do i start if i want to use a bootloader?

I have a PCB with a FTDI232BM chip that convert USB <--> RS232 signals and the PIC is a 18F2550, will it work to program via the FTDI chip or do i have to have a real USB connection?

Where can i download a bootloader for the PIC and a PC software to program the PIC?

[mister_e]

If you're using a USB PIC, you may want to use Microchip's Bootloader. (this one use the USB port) OR PICCoder

If you have MicroCode Studio plus, you already have bootloader firmware in... unless you have to purchase MicroCode Loader.(this one use RS-232 port)

Other option, is to find a freeware, I heard good comment on Tiny Bootloader.(also RS-232)

Once you have any bootloader firmware, you need to dump the firmware .HEX file in your PIC first by using your favourite PIC programmer.

Once it's done, you just need to compile your code and use your bootloader utility to update your PIC.

That's it!

EDIT: See difference from one bootloader to another... DEFINE LOADER_USED 1 have to be used.

[Fredrick]

Well that was easy.... Tiny Bootloader worked on the first try....
The loading time with Tiny bootloader is much faster then the PICkit2 programmer..

[mister_e]

hum, interesting to know. Thanks for your feedback.

[Fredrick]

Hmm i have now also try Microcode studio plus loader and that does´t work good..

I have loaded the right HEX file with my PICkit2 programmer and then when i try to "Compile and program" i get the message "Please reset the target microcontroller" and when i do that with the MCLR pin nothings happends... then i klick on the close button in the right corner of the window and now microcode loader starts to program the PIC, but i have to try severel times before the PIC works after the programming from the microloader.

[mister_e]

It will work all the time if you use their schematic as it add a connection to MCLR and you'll not need to do it yourself... hence why I'd modified my EasyPIC 4 board in the past.

http://www.mecanique.co.uk/code-studio/loader/reset-circuit.gif

[Fredrick]

But it should work to reset it manualy.

And when using microloader the programming time is slow.. my small testprogram takes about 6 secounds whit microloader and with Tiny Bootloader it takes "0.249 sec"...

[mister_e]

Yup, but MicroCode do more check than Tiny... this is why Microcode firmware is 'round 2.5 time bigger than Tiny.

Sometimes there's a price to pay if you want reliability or speed ;)

[Fredrick]

Yes that´s true.

But with microcode and manual reset i have to program the PIC severel times whit the same program before the PIC starts...

So i think something is wrong.

I will do some more tests and then give you some feedback here.

[Fredrick]

Why do you sometimes have the define
DEFINE BOOTLOADER_USED 1

Tiny bootloader works with and without this define so i wonder what does the define do?

[mister_e]

in fact it has to be

DEFINE LOADER_USED 1
What it does? From memory, It reserved the first 4 code location for the bootloader (1-2 nop and a GOTO to the bootloader code (at the end of the code space))

Why it works with Tiny... can't tell, maybe he correct the .hex file for you... but as it's a small program, you're not experimenting issue just yet.

Keep the DEFINE LOADER_USED 1 at the top.

[Fredrick]

Yes, thats why i trying to get the Microloader to work..

another question
Will a "software reset" work to get into the "bootloader mode"?

http://www.picbasic.co.uk/forum/showthread.php?t=899


Asm
bcf PCLATH, 3
bcf PCLATH, 4
goto 0
EndAsm


or has it to be a real MCLR reset?

[mister_e]

As you're using a 18F

@ RESET

should do. bootloader mode get out pretty fast of there, not like Tiny (which I can recall something like ~1 Sec before getting out)

[Fredrick]

Hmm... why does´t microloader work...

When i press the program button the message "Please restet the PIC in order to access bootloader process"

I press the reset button on the PCB (MCLR) and nothing happens..... i have to close the message window then the programming starts. is that normal?

Should´t the programming starts when i press the MCLR button?

[Fredrick]

Another thing with Microloader and Microcode studio plus is the way i have to set the COM port.

(I use a virutuel COM port, not a real one.)

If i run only the Microcode loader i can´t set the COM port at all, the dropdownlist is empty and "gray". if i run Microcode studio i can set the COM port via the ICD toolbar but when i use my PIC18F2550 i can´t so to set the right COM port i have to change the device to 16F628A and then change the COM port and then change the device back to 18F2550.

[HenrikOlsson]

Hi Fredrick,
The best way to do it is to add the connection to MCLR as per Steves previous message. It is rock-solid, I've been using ot for years. If you don't want to do that try holding down the Reset-button, click compile and program and when the program window pops up quickly release the reset-button.

The virtual COM port MIGHT be a problem, I've never had any problems personally but I've read about bad drivers and strange chip-sets in some of the cheap USB<->RS232 dongles.

[Fredrick]

This is the way my hardware looks like
http://www.olimex.com/dev/images/PIC/PIC-P28-USB-sch.gif

So i think that i just have to sold a wire from DTR pin from the FTDI chip to MCLR pin on the PIC with a 100ohm resistor in serie to get the software reset in microloader to work, right?

[mister_e]

In theory yes it has to work. Now the small timing issue you may have is the latency of the USB to serial converter. But I do remember to have successfully used some in the past.

Finger crossed.

One thing I would suggest to be really careful about is if you use ICSP later... MCLR have to go somewhere 'round 13Volts... not sure if your converter will like it... As Mackrackit says... "Always wear safety glasses while programming. :D"

[Fredrick]

Now i have a jumper from MCLR to the FTDI DTR pin via 100Ohms resistor and now the Microcode Loader works whitout any problems but the programming time is very slow about 10 sec for a 994 byts program, is there any way to speed that up?

But Microloader has a bug, if your computer does´t have any real serial ports you will not be available to change the COM port becouse the dropdownlist is locked and empty, however if you connect only one USB<-->Seriel cabel and then start the loader program the right com port will be selected and it work´s but the dropdownlist will still show "None" COM ports.

If you have a computer with a real serial port you will se both the real one and the virituel port in the dropdownlist.

And whitin MicroCode studio plus you will not be available to select the com port unless you change the device to a ICD compatibel PIC and then change the port and back to the PIC you are useing (in my case 18F2550.)

My Microcode Studio Version is 3.0.0.5

[mister_e]

Did you tried by changing the port and baudrate speed in the Mcloader application?

As far as i'm aware of, it set the baudrate to 9600, should work faster with higher speed OSC. It's been a long time I used a bootloader though :(

[Fredrick]

I have set it to the maximun speed 115200, the standard value was 19200.
And yes it´s a bit faster now and it still works ok, no programming errors.

Is the author of Microcode Studio on this forum?
Mayby he can release a bugfix for the COM port issue.

[mister_e]

Well it's not a com port issue, it's not even an issue, it's a hidden feature, and it's probably like that for reliability rather than for speed ;)

If you want to speed up a bit the process, you may uncheck some Verify options in MicroCode Loader option.

This said, the COM setting in MCSP is for ICD, not bootloader.

[Fredrick]

Yes, but I mean the issue with selecting the COM port in the loader app.

and in the help file for MCSP it says



Using the Loader with MicroCode Studio Plus

Connect a serial cable between your computer and development board. Apply power to the board.
From the ICD toolbar, select the serial port you will be using to communicate with the development board.


i can´t select any COM port there becous it´s locked, until i select an ICD compatibel PIC then i can change the port and then i have to change back to the PIC I´m using.

[mister_e]

Ah, I see, well let's forget the help file then :D

Not sure how bad some Virtual Port could be, but It may cause some problem with some Chipset/Driver combination.

Real serial port have their place, but agreed, not a big majority release serial product now... Even some PCI (or whatever else PC slot) are just silly priced now.

[Fredrick]

Yea...
Microcode studio plus is still the best editor for PBP that i know about. :D
Is there anyone here that are using a better editor?

[mister_e]

Define the word better and we may come up with some idea.

MPLAB is fine, but you don't have serial com port access, no plug-in facility either.

PsPad, nice code editor, but no PBP syntax embedded in

CodeDesigner was great a while back, no longer supported, no serial communication utility, no plug-in facility either.

[Fredrick]

I use PsPad as the default editor in windows, i like that editor, i have used Codedesigner in the past for PBP but switched to MCS and later to MCSP , MPLAB has so many functions that I don´t use there are just there to confuse me.

Microcode studio is simple to use without extra functions i don´t use and have a nice and clean interface with PBP syntax.

[F1CHF]

I got a board with a 16F874 and a Max 232 on board
(TX data and RX data goes to the normal PIC pins RC6 and RC7)

16F874 (20 Mhz) is OK (tested with a Blink program !)

SO, I try to use MCloader (version 1.0.1.7)
I burn bootloader file to the 16F874
I use my blink (Pic Basic pro 2.60) with the define user command
compilation ...
start MCloader ... reset MCLR .. nothing append .. still the message on MCloader about waiting a reset !
question :
is the DTR signal is used to reset the pic via the MAX232 and the 100 ohm resistor
is it used with the "software reset" option I see in MCloader setup

Can I use bootloader without this software reset option (I have just a push button on MCLR) ?
thanks.
Francois F1CHF

[HenrikOlsson]

Hi,
Yes, the DTR signal is used to remotely reset the PIC but you can easily use it without that feature, I do that all the time on one of my developement boards from SURE electronics. I hit Program and it asks me to reset the device - which I do - and it downloads the code to the device.

When it doesn't work it's usually because I've specified the wrong COM-port which happens to me from time to time, especially when using USB->COM dongles/adapters.

It's important that you flash the PIC with bootloader.hex file for the correct oscillator speed (20MHz in your case) and that you put DEFINE LOADER_USED 1 in your program.

/Henrik.

[F1CHF]

OK Henrick
Thanks for your reply
I use a laptop with one COM port (and in MCloader there is no more choice than COM1)
this COM1 is working with my serial programmer
It is important that you said ...

TX and RX lines (via MAX232) goes to RC6 and RC7
good bootloader file burned in the pic (16F874_20.hex from MCloader directory)
compilation (using PBP v 2.6) using good define user line (this program "blink" was tested and PIC is OK)
power on the PIC
start MCloader .. load hex file ... push program icon .... depress RESET button on PIC board

download should works beetween the laptop and te PIC ...

am I right ?

[HenrikOlsson]

Hello,
Yes, when you press Program there should pop up two messages/windows, first one with a progress bar that says Programming and then, when it can't reset the PIC, a second one saying Please reset target microcontroller in order to access the bootloader process... When you reset the PIC the second window will close and you can monitor the progress in the first window, it only takes a couple of seconds depending on the size of the program.

Have you verified that the serial communication is working, ie by using HSEROUT/HSERIN to send and receive data. Perhaps you've mixed up the RX/TX lines?

/Henrik.

[F1CHF]

Same player shout again
I am still in the same marmelade !
I have checked the hardware RX TX max232 seems good (no mix)
I will try to test as you said (transmit between PIC and laptop)
I suspect also that my programmer is not wonderfull
I must program sometimes 5 times to avoid errors
I must compare iniatial file from MCloader (16F874_20.hex) with the data burned in the pic !
I have tried with two differents PIC

for this week I will be out for 3 days, so, hold the line !
I lost already 3 days on this crazy thing, no problem because I am retired ! hi ...
Francois

[F1CHF]

Still me, with the same problem
I spent one day without success !
abstract : I got garbage using Hserout (to test my RS232 line for bootloader function)
see my terminal V1.9 log file (hexa dump and ascii dump)
question :
What is wrong in my design ?
I have tested in XT and HS clock mode
I have changed the MAX232
LCD and Blink led seems normal (pic is alive !)
I am lost !
Thnaks in advance
Francois

the program test is the following :
' Using PIC 16F874 @ 20MHZ
'
DEFINE OSC 20
' Set LCD Data port
DEFINE LCD_DREG PORTD
' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_DBIT 4
' Set LCD Register Select port
DEFINE LCD_RSREG PORTD
' Set LCD Register Select bit
DEFINE LCD_RSBIT 2
' Set LCD Enable port
DEFINE LCD_EREG PORTD
' Set LCD Enable bit
DEFINE LCD_EBIT 3
' Set LCD bus size (4 or 8 bits)
DEFINE LCD_BITS 4
' Set number of lines on LCD
DEFINE LCD_LINES 2

' Hardware configuration
' ======================
TRISC = %10000000 ' PORTC.7 is the RX input
' PORTC.6 is the TX output

' Serial communication definition
' ===============================
' Using internal USART and MAX232 to interface to PC

DEFINE HSER_RCSTA 90h ' enable serial port, enable continuous receive
DEFINE HSER_TXSTA 20h ' enable transmit, BRGH=1
DEFINE HSER_SPBRG 129 ' 2400 Baud @ 20MHz, 0,17%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

Pause 500

start:
high portd.1
pause 100
low portd.1

lcdout $FE ,1,"test"
pause 500
lcdout $FE ,1, "to see"
pause 500


hserout ["test TEST"]
pause 1000
goto start

[F1CHF]

Stop it works !
Now I have the solution to lost one week !
use a bad Xtal/quartz !
Pic was running at 6 khz ! instead of 20 Mhz

just one thing ... put HS (high speed) at the config time(first load) for the bootloader
second think ... close your terminal program to avoid conflict during MCloader time !

Thanks for helping me ..
Francois