Trigger IO

Component Type: Output

Status: Implemented

Overview

CIOTrigger is a special-purpose write-only IO that fires one-shot commands on bound objects (IOs, Programs, or Protocols) while they are running.

Supported commands:

RESET -> reset internal state of bound objects (e.g. clear accumulators)
TRIGGER1 -> object-specific action slot 1 (e.g. ADC single conversion)
TRIGGER2 -> object-specific action slot 2
TRIGGER3 -> object-specific action slot 3

Commands are dispatched through the trigger(cmd) virtual method on CObject. Objects that do not implement a given command return -ENOTSUP and are silently skipped. Each instance uses an allowed_cmds bitmask that restricts which commands it may issue.

A single Trigger IO can be bound to multiple objects of any type (IO, PROG, PROTO). Read is not supported (isRead() returns false).

Differs from Control IO (which manages lifecycle start/stop state) and Config IO (which controls configuration data values).

Implementation

CIOTrigger is a control-only IO that fans out a single command byte (reset, trigger1, trigger2, trigger3) to one or more bound CObject targets. IO_TRIGGER_CFG_ALLOWED is a bitmask of permitted commands; attempts to issue a disallowed command return -EACCES. Targets are resolved during CDawn::bindObjects() from the IDs supplied via IO_TRIGGER_CFG_ALLOCOBJ. Read operations always return -ENOTSUP.

Data Format

Write operations use a single uint8_t byte containing the command code:

Value	`CObject` constant	Description
`0`	`CObject::CMD_RESET`	Reset internal state
`1`	`CObject::CMD_TRIGGER1`	Object-specific action slot 1
`2`	`CObject::CMD_TRIGGER2`	Object-specific action slot 2
`3`	`CObject::CMD_TRIGGER3`	Object-specific action slot 3

Allowed Commands

The allowed bitmask restricts which commands a given instance may issue. Attempting a disallowed command returns -EACCES.

Flag	Value	Description
`TRIG_ALLOW_RESET`	`(1 << 0)`	Allow `CMD_RESET`
`TRIG_ALLOW_TRIGGER1`	`(1 << 1)`	Allow `CMD_TRIGGER1`
`TRIG_ALLOW_TRIGGER2`	`(1 << 2)`	Allow `CMD_TRIGGER2`
`TRIG_ALLOW_TRIGGER3`	`(1 << 3)`	Allow `CMD_TRIGGER3`

Configuration

Kconfig

CONFIG_DAWN_IO_TRIGGER: enables the Trigger IO.

YAML

ios:
  - id: trig1
    type: trigger
    config:
      targets:
        - sampling1
      allowed:
        - trigger1
        - trigger2

Supported allowed values: reset, trigger1, trigger2, trigger3.

External Control

ControlIO: not supported.

TriggerIO: implemented by this IO.

Doxygen

dawn::CIOTrigger