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We want to keep the tri-state buffers located between the FPGA and the board, in 'Z' state until we launch an i2c connection. We launch an i2c start condition, make the SCL direction 'OUT' to start the i2c protocol and at the end of the i2c connection at the stop condition, we re-make the tri-state buffers at 'Z' state. Change-Id: Ic597a70d0427832547f6b539864c24ce20a18c64 Signed-off-by: Ahmed BOUDJELIDA <aboudjelida@nanoxplore.com> Reviewed-on: https://review.openocd.org/c/openocd/+/7989 Tested-by: jenkins Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com> |
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#SPDX-License-Identifier: GPL-2.0-or-later This is the ANGIE firmware for ANGIE USB-JTAG adapter. The main components of ANGIE adapter are: - Cypress EZ-USB FX2 microcontroller - Spartan-6 FPGA - SRAM memory chip - Pin headers for various JTAG pin assignments To compile the firmware, the SDCC compiler package is required. Most Linux distributions include SDCC in their official package repositories. The SDCC source code can be found at http://sdcc.sourceforge.net/ Simply type "make bin" in the ANGIE directory to compile the firmware. "make clean" will remove all generated files except the BIN file required for downloading the firmware to ANGIE. Note that the EZ-USB FX2 microcontroller does not have on-chip flash, ANGIE include on-board EEPROM memory to store the firmware program of the FX2, but we are not going to use this method. Instead, upon initial connection of the ANGIE adapter to the host PC via USB, the EZ-USB FX2 core has enough intelligence to act as a stand-alone USB device, responding to USB control requests and allowing firmware download via a special VENDOR-type control request. Then, the EZ-USB microcontroller simulates a disconnect and re-connect to the USB bus. It may take up to two seconds for the host to recognize the newly connected device before OpenOCD can proceed to execute JTAG commands. This delay is only visible when OpenOCD first uses a blank (unconfigured) ANGIE device. Once the firmware downloaded, the FX2 microcontroller activate its GPIF mode, download the Spartan-6 FPGA's bitstream, program the FPGA rapidly, and switch back to default io mode. Once the user disconnects the ANGIE adapter, all its memory contents are lost and the firmware & bitstream download process has to be executed again.