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Can anyone pls explain the max limit to be given for delay "_delay_ms()" identifier in xc16 compiler in MPLAB for dspic33ep256mu814 controller?

Thanks in advance.

maxy
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  • JTAG is a very specific but generic set of signals and protocol, not intended for this purpose. But has been used to access logic within a chip/processor which in some devices can be used to access the flash directly or can be used to talk to the processor, take over its bus, and through that program the flash. – old_timer Jan 02 '20 at 16:21
  • you generally do not use JTAG to talk to software, the bootloader is a program that runs first or depending on the part using a strap (an input pin tied high or low a the right time after reset) tells the logic to boot the bootloader instead of the main application. the the bootloader has some interface uart, i2c, spi, custom that is used to communicate and some external hardware/software can be used to ask the bootloader to write to flash, understanding that the bootloader itself has to be out of the way – old_timer Jan 02 '20 at 16:22
  • there are jtag like but not jtag things with names like TWI, PDI, SWD, etc that are used in a similar way but intended for programming the flash and/or talking to an on chip debugger that can take over the processor and/or its bus. and then through that reprogram the flash. – old_timer Jan 02 '20 at 16:24
  • shorter higher level answer. jtag means using something outside the part to reach in. bootloader means software inside the part programming the flash, that you communicate with via something outside the part. jtag: hardware path into the part, bootloader: software path into the part. – old_timer Jan 03 '20 at 16:20

1 Answers1

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Can we update firmware in microcontroller using JTAG?

It depends on your microcontroller. See its data sheet and other documentation.

What is the diffrence between JTAG and bootloader programming in microcontroller?

  • The JTAG interface is a hardware based method. You might look at it as if you can access internal control lines, for example to write or read specific memory cells. No software is involved on the microcontroller's side. The JTAG standard defines a serial interface on a very low level.

  • Bootloader programming needs a small application in the microcontroller: the bootloader. It might use any hardware interface (like a serial line) and any protocol, for example to access internal flash memory. Some microcontroller are sold with a bootloader.

the busybee
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