daphne

CMSIS-DAPv2 probe hackery, specifically for playing with my Raspberry Pi Debug Probe.

.
├── dapcap/        # Utility for sniffing CMSIS-DAPv2 packets over USB
├── daphne/        # Library crate
├── daphne-server/ # Server binary crate
└── README.md      # (You are here)

Caution

This is not a "complete" implementation in any sense, and important details from various specifications (CMSIS-DAP, ADIv5, CoreSight, JTAG, SWD, etc.) may be only partially represented or otherwise totally absent from this library. This works for my particular use case, but there are no hard guarantees in other cases.

Additionally, note that the server and library currently make assumptions based on my own environment with the Raspberry Pi 5. For instance:

• There is no JTAG support
• The USB backend assumes the PID/VID of the Raspberry Pi Debug Probe
• Some SWD primitives are hardcoded to target DAP index 0
• SWD DAP initialization may not be generalizable to other devices

This library has two parts:

• A daphne-server binary crate, which manages communication between the target and some client program on the host machine

• A daphne library crate, used to write client programs

Server Usage

When running client programs, daphne-server must be running in the background in order to actually communicate with the target device.

$ git clone https://github.com/eigenform/daphne && cd daphne
...

$ cargo build --release --bin daphne-server
...

# Start the server
$ ./target/release/daphne-server
...

Client Usage

The library crate includes a DaphneClient type that exposes methods for connecting to the DAP on a target machine and performing DP/MEM-AP accesses. CMSIS-DAP transactions are handled transparently by the server. For example:

use daphne::prelude::*;

// Connect to the server
let mut cli = DaphneClient::connect()?;

// Connect to the DAP 
cli.send(DaphneOp::Dap(DapOp::Connect))?;

// Perform a DP read operation
let resp = cli.send(DaphneOp::Dp(DpOp::Read { reg: DpRegister::DPIDR }))?;
println!("[*] DPIDR: {:08x?}", resp);

// Perform a MEM-AP read operation
let dbg = DebugBlock { base: 0x8001_0000 };
let resp = cli.send(DaphneOp::MemApBus(MemApBusOp::Read { 
    ap: 0, addr: dbg.addr_of(Armv8ExtDbgReg::MIDR),
}))?;
println!("[*] MIDR: {:08x?}", resp);

License

This project is MIT licensed (see LICENSE-MIT), and was originally based on adamgreig/jtagdap, which is dual-licensed under either APLv2 or MIT. The original MIT license text is preserved here in LICENSE-MIT.jtagdap.