![]() The target id has different meaning for the different requests. Details for the request byte Bit 7 6 5 4 3 2 1 0 Four HD44780 command bytes or four HD44780 data bytes can thus be transferred during one USB transaction. These are used to transmit up to four data bytes per transfer. The remaining four bytes (two bytes value and two bytes index) are left for the data transfer. The LCD2USB protocol does not send extra data, thus the last two bytes should be 0 for compatibility reasons. The remaining seven bytes are the request type (1 byte), a value (2 bytes), an index (2 bytes) and a length field (2 bytes) for data being transmitted with the control transfer. used to request the device name and id etc). The first byte indicates the control type and has to be set to a fixed value for vendor specific commands like the LCD2USB is using for its own purposes (non vendor specific commands are e.g. A USB control message for a low speed device consists of exactly 8 Bytes. More efficient and faster bulk transfers are only available to high speed devices. Protocol descriptionįor simplicity reasons, the LCD2USB interface only uses USB control messages. But you'll probably have to do some minor adjustments in the Makefile. If your are familiar with a different AVR programming system you can of course use that one as well. To manually upload the firmware using the usbasp just use the follwing command: avrdude -c usbasp -p atmega8 -U lfuse:w:0x9f:m -U hfuse:w:0xc9:m -U flash:w:firmware-avrusb.hex If the Makefile doesn't work for you you can also flash the device manually using avrdudeand the aforementioned STK200 compatible printer port adapter with the following parameters: avrdude -c stk200 -p atmega8 -U lfuse:w:0x9f:m -U hfuse:w:0xc9:m -U flash:w:firmware-avrusb.hex Connect it via the download cable and the programming adapter to the linux pc with installed uisp tool and type "make fuse make flash-nodep" to upload the firmware. It will not be detected yet, since it doesn't contain the firmware. The Makefile in lcd2usb/firmware/Makefile assumes, that you are using a simple STK200 compatible printer port adapter.Ĭonnect the assembled device (no display required yet) via USB to the PC. If you are familiar with Atmel programming you probably know what you are doing. ![]()
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