jtag no serial
KoRGeNeRaL said:
Thanks for the response.
Does this mean that even if a board has a usb connector and a uC which can have a bootloader, it can reqire a jtag adapter to be programmed?
Well the first thing you want to do is pick a board, and then verify this is true.
For example, let's look at Keil's MCB2100 at
https://www.keil.com/mcb2100/. This board has an NXP LPC2103 chip. The LPC2103 has an on-chip bootloader (not all ARM chips have a bootloader, it depends on the vendor, not ARM).
The on-chip bootloader for the LPC2103 always uses serial port 0. And the MCB2100 has a DB9 connector for serial port 0. So you can load code through serial port 0 on this board without a JTAG, no problem. What happens is that when you power on the LPC2103 and it is empty (no code from the factory), it starts looking for a new code download on serial port 0.
If the board did not have a DB9 connector, you couldn't load code with the bootloader. Why? Because even though there is a bootloader on the NXP chip, there is no serial port connection on the board.
So it is important to choose the processor
and the board design carefully.
There are other chips (I think Atmel?) where the bootloader is via USB, not serial. So for those chips, make sure the board has a USB connector, so you can talk to the bootloader with a PC.
So in summary, you need to make sure the processor on the board has an on-chip bootloader, AND that the board has a connector (USB or serial, depending on the chip) that connects to the port on the processor that is used by the bootloader. I hope I explained that well.
KoRGeNeRaL said:
If it doesn't mean that, then i should be able to program any arm7 board which has an usb connector by using the bootloader.
This statement isn't always true, it depends on the board and the processor. I hope the explanation above shows why.