i8254

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Provided by: 8254
Class Hierarchy: conf-object → log-object → i8254
Interfaces Implemented: log_object, event_poster, io_memory
Ports: Gate2 (signal), Gate1 (signal), Gate0 (signal)
Description: The i8254 device implements the functionality of the PIT (Programmable Interval Timer) counter device found in most PCs. In a real system it is used to generate interval signals for the TOD clock, DMA refresh, and the speaker. The simulated device is only connected to the interrupt device; it counts internally, and the value can be read and written from the processor. The 8254 device also implements Port B in the 8255 PPI (Programmable Peripheral Interface). This port is used to control the builtin PC speaker. Counting mode 1, and BCD counting is not implemented.

Attributes inherited from class conf-object

attributes, classname, component, iface, name, object_id, queue

Attributes inherited from class log-object

access_count, log_buffer, log_buffer_last, log_buffer_size, log_group_mask, log_groups, log_level, log_type_mask

Attribute List

bcd: Optional attribute; read/write access; type: [iii]|[iiii].
The counting format for each counter (0 or 1).

beep: Optional attribute; read/write access; type: Integer.
Set to 1 if a beep is currently playing in the speaker. Only valid if the have_speaker attribute is 1.

clock_freq_hz: Optional attribute; read/write access; type: [fff]|[ffff].
Clock input frequencies for the counters, in Hz. Defaults to 1193180.0 Hz for all counters. The frequency should be set before simulation starts.

cmd: Optional attribute; read/write access; type: [iii]|[iiii].
The RW command for each counter.

cmd_names: Pseudo attribute; read-only access; type: [ssss].
List of all command names.

count: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four count values, one for each counter.

counting: Optional attribute; read/write access; type: [iii]|[iiii].
For each of the four counters, a flag indicating whether it is running.

gate: Optional attribute; read/write access; type: [iii]|[iiii].
Four gate signals (1 or 0], one for each counter.

have_speaker: Optional attribute; read/write access; type: Integer.
Set to 1 (default) if counter 2 is connected to a standard PC speaker.

initial_count: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four initial count values, one for each counter.

initial_time: Optional attribute; read/write access; type: [fff]|[ffff].
For each of the four counters, a time stamp indicating when the counter was last restarted (in floating-point format)

interrupt_pin: Optional attribute; read/write access; type: Integer.
Interrupt request status.

irq_dev: Optional attribute; read/write access; type: Object or Nil.
Device to send interrupts to, that implements the simple-interrupt.

irq_level: Optional attribute; read/write access; type: Integer.
Interrupt level for the interrupt device.

latched: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four flags, each set to 1 if the corresponding counter has a latched value.

latched_count: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four latched values, one for each counter.

latched_s: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four flags, each set to 1 if the corresponding counter has a latched status.

latched_status: Optional attribute; read/write access; type: [iii]|[iiii].
A list of four latched status bytes, one for each counter.

mode: Optional attribute; read/write access; type: [iii]|[iiii].
The PIT counting mode for each counter (0 - 5).

mode_names: Pseudo attribute; read-only access; type: [ssssss].
List of all mode names.

next_read_high: Optional attribute; read/write access; type: [iii]|[iiii].
For each of the four counters, a flag indicating if the next read access is for the high byte.

next_write_high: Optional attribute; read/write access; type: [iii]|[iiii].
For each of the four counters, a flag indicating if the next write access is for the high byte.

null_count: Optional attribute; read/write access; type: [iii]|[iiii].
The 'null count' status bit.

out: Optional attribute; read/write access; type: [iii]|[iiii].
Output values (0 or 1], one for each counter.

refresh_clock: Optional attribute; read/write access; type: Integer.
Bit 4 when reading from port B.

speaker: Optional attribute; read/write access; type: Integer.
Enable flag for speaker, only valid if the have_speaker attribute is 1.

Commands defined by interface log_object

log, log-group, log-level, log-size, log-type

Commands

info	print information about the device
status	print status of the device

<i8254>.info
Synopsis: <i8254>.info
Description: Print detailed information about the configuration of the device.

<i8254>.status
Synopsis: <i8254>.status
Description: Print detailed information about the current status of the device.

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