systemview-target

RTOS tracing trait implementation for SEGGER SystemView.

SEGGER SystemView can be used for free in non-commercial projects.

Features

• callbacks-os: Check if RTOS supports tracing callbacks from SystemView.
• callbacks-os-time: Check if RTOS supports timestamp callback from SystemView.
• callbacks-app: Check if your application supports callback from SystemView.
• log: Activates global log over RTT.
• cortex-m: Enables Arm Cortex-M support.
• ext-rtt-channels-*: Co-existence with other RTT clients (e.g. defmt).

Usage

If you are using an RTOS which supports rtos-trace add the following dependencies:

# Cargo.toml
[dependencies]
rtos-trace = "0.2"
systemview-target = { version = "0.3", features = ["log", "callbacks-app", "callbacks-os", "callbacks-os-time", "cortex-m"] }
log = "0.4"

and add to your code

// for tracing
use systemview_target::SystemView;
rtos_trace::global_trace!{SystemView}

static SYSTEMVIEW: systemview_target::SystemView = systemview_target::SystemView::new();

fn main() -> ! {
    SYSTEMVIEW.init();
    // for logs
    log::set_logger(&SYSTEMVIEW).ok();
    log::set_max_level(log::LevelFilter::Trace);
    /*..*/
}

Co-existence with other RTT clients (e.g. defmt)

By default this crate defines the _SEGGER_RTT symbol. This conflicts with other crates like defmt_rtt which declare the same global symbol.

To use this crate with defmt or other RTT clients, let your application depend on rtt-target rather than the defmt_rtt crate and enable one of the ext-rtt-channels-[N] features of this crate.

The parameter N is an integer and defines the overall number of externally allocated RTT channels.

Note: This feature requires at least version 0.2.1 of the systemview-target crate and 0.6.2 of the rtt-target crate.

Safety

The following conditions must be met by your application, otherwise it will expose undefined behavior:

• The integer N of the enabled ext-rtt-channels-[N] feature must correspond exactly to the number of externally allocated channels.

• At least one up and down channel must be allocated without a buffer (see example below).

• Both pre-allocated channels must have the same channel id.

Note: Currently we only support symmetric configurations, i.e. the number of available up and down channels must be equal.

Example

To use systemview-target with defmt let your crate depend on rtt-target and enable the appropriate feature corresponding to the number of channels defined in your application. In this example we'll define two RTT channels:

# Cargo.toml
[dependencies]
defmt = "1.0"
rtos-trace = "0.2"
rtt-target = "0.6.2"
systemview-target = { version = "0.3", features = ["ext-rtt-channels-2", ...] }

Then we declare the RTT control block and defmt channel explicitly:

use systemview_target::SystemView;
rtos_trace::global_trace!{SystemView}

static SYSTEMVIEW: systemview_target::SystemView = systemview_target::SystemView::new();

fn main() -> ! {
    let channels = rtt_init! {
        up: {
            0: { size: 1024, name: "Terminal" }
            1: { } // Pre-allocated RTT channel for SystemView.
        }
        down: {
            0: { size: 16, name: "Terminal" }
            1: { } // Pre-allocated RTT channel for SystemView.
        }
    };

    set_defmt_channel(channels.up.0);

    // Initialize SystemView _after_ allocating its RTT channel.
    SYSTEMVIEW.init();
}

Segger's SystemView code will now identify, allocate and use RTT channel one while defmt owns channel zero.