DotMatrix

caution

This service is rc and may change in the future.

A rectangular dot matrix display, made of monochrome LEDs or Braille pins.

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()

Registers

dots

The state of the screen where dot on/off state is stored as a bit, column by column. The column should be byte aligned.

For example, if the display has no more than 8 rows in each column, then each byte contains bits corresponding to a single column. Least-significant bit is on top. If display has 10 rows, then each column is represented by two bytes. The top-most 8 rows sit in the first byte (with the least significant bit being on top), and the remainign 2 row sit in the second byte.

The following C expression can be used to check if a given column, row coordinate is set: dots[column * column_size + (row >> 3)] & (1 << (row & 7)), where column_size is (number_of_rows + 7) >> 3 (note that if number of rows is 8 or less then column_size is 1), and dots is of uint8_t* type.

The size of this register is number_of_columns * column_size bytes.

• type: Register<Buffer> (packing format b)

• track incoming values

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
dotMatrix.dots.subscribe(async (value) => {
    ...
})

note

write and read will block until a server is bound to the client.

intensity

Reads the general brightness of the display, brightness for LEDs. 0 when the screen is off.

• type: Register<number> (packing format u0.8)

• optional: this register may not be implemented

• read and write

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
const value = await dotMatrix.intensity.read()
await dotMatrix.intensity.write(value)

• track incoming values

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
dotMatrix.intensity.subscribe(async (value) => {
    ...
})

note

write and read will block until a server is bound to the client.

rows

Number of rows on the screen

• type: Register<number> (packing format u16)

• constant: the register value will not change (until the next reset)

• read only

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
const value = await dotMatrix.rows.read()

note

write and read will block until a server is bound to the client.

columns

Number of columns on the screen

• type: Register<number> (packing format u16)

• constant: the register value will not change (until the next reset)

• read only

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
const value = await dotMatrix.columns.read()

note

write and read will block until a server is bound to the client.

variant

Describes the type of matrix used.

• type: Register<number> (packing format u8)

• optional: this register may not be implemented

• constant: the register value will not change (until the next reset)

• read only

import { DotMatrix } from "@devicescript/core"

const dotMatrix = new DotMatrix()
// ...
const value = await dotMatrix.variant.read()

note

write and read will block until a server is bound to the client.