Hi! On Tue, Jan 9, 2024 at 10:34 PM John Crispin <j...@phrozen.org> wrote: > > > On 09.01.24 14:51, Chuanhong Guo wrote: > > Hi! > > > > On Tue, Jan 9, 2024 at 6:52 PM John Crispin <j...@phrozen.org> wrote: > >> [...] > >> FAQ > >> > >> * Why are there are 2 different flash chips? > >> - the idea is to make the device (almost!) unbrickable and very easy to > >> recover > > What about a built-in JTAG probe instead of SPI-NOR+USB-UART? > > It'll be actually unbrickable instead. > > > >> - NAND will hold the main loader (U-Boot) and the Linux image and will > >> be the default boot device > >> - NOR will be write-protected by default (with WP jumper available on > >> the board) and will hold a recovery bootloader (and other essential > >> data, like Wi-Fi calibration) > >> - a dedicated boot select switch will allow changing between NOR and NAND > >> [...] > >> * What is the purpose of the console USB-C port? > >> - Holtek UART to USB bridge with CDC-ACM support on USB-C makes the > >> device ultra easy to communicate with. No extra hardware or drivers will > >> be required. Android for example has CDC-ACM support enabled by default > > There are several MCU-based CMSIS-DAP projects out there. They can > > provide a CDC-ACM serial with a JTAG interface. It may be a bit slow if a > > USB1.1 MCU is picked, but it should be enough to start a bootloader to > > unbrick the device. > > > > Here's one with USB2.0 Hi-speed interface: > > https://github.com/cherry-embedded/CherryDAP > > The Sipeed M0S module used costs 20CNY on Taobao > > (or 2.81 USD according to google) > > we looked into that kind of solution, i felt more accessible for the > wider audience to use a CDC-ACM chip. flashing using a DAP involves > knowing what JTAG is and how to use it. the idea is that the NOR uboot > has a backup copy of the NAND uboot. holding down one of the buttons > while powering on the device while BOOTSEL is on NOR will auto recover > the NAND. cannot think of a simpler solution.
My thought was that all the JTAG stuff can live in a script. But I agree that yours are definitely easier for end user :D -- Regards, Chuanhong Guo _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel