> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 >=20 > On Sun, 24 Mar 2013 21:14:55 +0800 > Xiaofan Chen wrote: >=20 > > Microchip's USB Stack seems to be not bad if compared to > > other vendors' USB Stack. It has the USB HID Bootloader > > which has a cross-platform host software (based on hidapi) > > as well. It is not burned into ROM though. > >=20 > > The good thing about using the HID class is that it does > > not need a driver under Windows whereas DFU class > > requires a driver under Windows since Microsoft does > > not offer OS built-in DFU USB driver. >=20 > The last sentence of the first paragraph above is the only one that > really matters to me. If it=B4s not in ROM, then that means you have to > burn it into the chip some other way first. For DIPs that=B4s no big > deal. For TQFPs, it means you put a programming header on your > application board. If your objective was to save space by reusing a USB > socket already present, adding a programming header anyway means you > have failed, and (to me) there is no longer any reason to have the > bootloader. The main purpose of a bootloader must surely be to let the end user be able= to=20 upgrade the firmware in the field without a dedicated programmer. While developing, you still need the ISCP header to debug the board. And it= =20 doesn't need to be a header - I have done some small boards with just pads = or=20 small vias and used a fixture with "pogo pins" to connect to the board. And what if you want to load the firmware with a UART or Ethernet connectio= n=20 and don't use USB at all in that design? Does the ROM based bootloader hand= le=20 that also? I can see the benefit to be able to load the firmware at production with a = ROM=20 based bootloader but it is not something I would like to pay for (because i= t=20 must come at a cost) if I am not using it. Which is probably why the majori= ty=20 of MCUs comes without a ROM based bootloader. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Ruben J=F6nsson AB Liros Electronic Box 9124 200 39 Malm=F6 Sweden www.liros.se Tel +46 40142078 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .