Crate jaylink

A crate for talking to J-Link debug probes connected via USB.

This crate allows access to the vendor-specific USB interface used to control JTAG / SWD operations and other functionality. It does not provide access to the virtual COM port functionality (which is a regular CDC device, so no special support is needed).

Inspired by libjaylink (though this library is not a port).

Pinout

J-Link uses a pinout based on the standard 20-pin ARM JTAG connector, extended for SWD compatibility and with pins for UART.

JTAG pinout:

           ┌───────────┐
    VTref  │ *  1  2 * │ NC
    nTRST  │ *  3  4 * │ GND
      TDI  │ *  5  6 * │ GND
      TMS  │ *  7  8 * │ GND
      TCK ┌┘ *  9 10 * │ GND
     RTCK └┐ * 11 12 * │ GND
      TDO  │ * 13 14 * │ GND
    RESET  │ * 15 16 * │ GND
    DBGRQ  │ * 17 18 * │ GND
5V-Supply  │ * 19 20 * │ GND
           └───────────┘

SWD (+ UART) pinout:

           ┌───────────┐
    VTref  │ *  1  2 * │ NC
        -  │ *  3  4 * │ GND
J-Link TX  │ *  5  6 * │ GND
    SWDIO  │ *  7  8 * │ GND
    SWCLK ┌┘ *  9 10 * │ GND
        - └┐ * 11 12 * │ GND
      SWO  │ * 13 14 * │ GND
    RESET  │ * 15 16 * │ GND
J-Link RX  │ * 17 18 * │ GND
5V-Supply  │ * 19 20 * │ GND
           └───────────┘

Reference

Segger has released a PDF documenting the USB protocol: "Reference manual for J-Link USB Protocol" (Document RM08001-R2).

The archive.org version is the most up-to-date one.

Structs

BitIter	An iterator over a received bit stream.
Capabilities	Set of capabilities advertised by the device.
CommunicationSpeed	Target communication speed setting.
Error	The error type used by this library.
HardwareVersion	A hardware version returned by JayLink::read_hardware_version.
Interfaces	Bitset of supported target interfaces.
JayLink	A handle to a J-Link USB device.
Speeds	J-Link CPU frequency info.
UsbDeviceInfo	Generic info about a USB device.

Enums

ErrorKind	List of specific errors that may occur when using this library.
HardwareType	The hardware/product type of the device.
Interface	List of target interfaces (JTAG / SWD).

Functions

scan_usb

Scans for J-Link USB devices.

Type Definitions

Result

A result type with the error hardwired to Error.