> For the complete documentation index, see [llms.txt](https://tk233.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tk233.gitbook.io/notes/electrical/openocd-and-ftdi-chips.md). # OpenOCD and FTDI Chips To let OpenOCD correctly drive the FTDI chip, we need to tell OpenOCD the hardware configuration of the FTDI chip through the config file: ```properties ### FTDI interface configuration ### ftdi_vid_pid 0x0403 0x6010 ftdi_channel 0 ftdi_layout_init 0x0888 0x8B8B ``` Reference: We will analyze the config file line by line ```properties ftdi_vid_pid 0x0403 0x6010 ``` This line tells OpenOCD to find the USB device with the signature of corresponding vendor ID (VID) and product ID (PID). 0x0403: [Future Technology Devices International Limited](https://the-sz.com/products/usbid/index.php?v=0x0403) 0x6010: FT2232C/D/H Dual UART/FIFO IC ```properties ftdi_channel 0 ``` Selects the channel of the FTDI device to use for MPSSE operations. Here we select channel A, which is the first channel (channel 0). ```properties ftdi_layout_init 0x0800 0x0800 ``` Defines the initial data and IO direction of the GPIOs. The mapping is as follows: | 0x | bit \[15..8] | bit \[7..0] | | -- | ------------ | ------------ | | | ACBUS\[7..0] | ADBUS\[7..0] | As an simple example, to initialize the JTAG LED on FT-LINK, which is an open-drain LED connected to ACBUS3 pin, we use the following setting ```properties ftdi_layout_init 0x0800 0x0800 # this initialize LED off ``` ```properties ftdi_layout_init 0x0000 0x0800 # this initialize LED on ``` We can also define the JTAG\_LED variable with the following command ```properties ftdi_layout_signal JTAG_LED -oe 0x0800 ``` Then, in the init routine, we can use the variable to reference this pin and blink the LED ```properties init ftdi_set_signal JTAG_LED 0 # LED on sleep 1000 ftdi_set_signal JTAG_LED z # LED off sleep 1000 ftdi_set_signal JTAG_LED 0 # LED on ``` note that since we are only enabling the output driver by the `-oe` flag, the chip can only drive it open-drain, and therefore we are only allow to set the signal state to either low (`0`) or high-Z (`z`). If we try to set it to high (`1`), we will get the following error: ```bash Error: interface can't drive 'JTAG_LED' high ``` If we have some normal signal that we want to drive both high and low, we can use the `-data` flag instead: ```properties ftdi_layout_signal JTAG_LED -data 0x0800 ``` ```properties init ftdi_set_signal JTAG_LED 0 # LED on sleep 1000 ftdi_set_signal JTAG_LED 1 # LED off sleep 1000 ftdi_set_signal JTAG_LED 0 # LED on ``` If we somehow want all the states, we do the following ```properties ftdi_layout_signal JTAG_LED -data 0x0800 -oe 0x0800 ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://tk233.gitbook.io/notes/electrical/openocd-and-ftdi-chips.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.