Ctrlk
For the complete documentation index, see llms.txt. This page is also available as Markdown.
ChatGPT

Show Image

Command 0x1821 - Show Image (Display Only)

The host uses this command to trigger the device to immediately show a pre-loaded image on the display, provided the device is not in a mode that has exclusive use of the display (such as during a transaction). This is an immediate and temporary directive. For a solution that affects the device’s idle page behavior on a more permanent basis, see Property 1.2.3.1.1.1 Custom Idle Page Image. This command is different from Command 0x1823 - Show Bitmap Image in that the bitmaps are pre-loaded and persistently stored in the device and can not be composited with each other.

The sequence of events is as follows:

1

Prepare the image slot

The host makes sure it has loaded the image into at least one of the device’s Custom Idle Page Image slots using Command 0xD812 - Start Send File to Device (Unsecured).

2

Ensure device is in Active/Idle

The host makes sure the device is in Active/Idle state (meaning the display is fully powered on and is not in a mode that has exclusive use of the display, such as processing a transaction).

3

Call the Show Image command

The host calls this command to show the image loaded into the desired slot number.

4

Display behavior

The device shows the specified image on the display until the device is no longer in Active/Idle.

Table - Request Data for Command 0x1821 - Show Image (Display Only)

Tag
Len
Value / Description
Typ
Req
Default

Beginning of any wrappers, at minimum including Request Message

1821 = Command 0x1821 - Show Image (Display Only)

81

01

Custom Idle Page Image Number

  • 0x01 = Show custom image 1

  • 0x02 = Show custom image 2

  • 0x03 = Show custom image 3

  • 0x04 = Show custom image 4

B

R

82

01

Display Option

  • 0x00 = Default to cover/uncover the top status bar depends on the current status of the display. If the current display shows the top status bar, the Show Image command won’t cover the top status bar. If the current display doesn’t show the top status bar, the Show Image command will cover the top status bar.

  • 0x01 = Cover the top status bar regardless of the current status of the display.

  • 0x02 = Not cover the top status bar regardless of the current status of the display.

B

O

0

83

01

Display Time

  • 0x00 = Show image until device changes state

B

O

0

End of any wrappers, at minimum including Request Message

Table - Response Data for Command 0x1821 - Show Image (Display Only)

Tag
Len
Value / Description
Typ
Req
Default

Beginning of any wrappers, at minimum including Response Message

1821 = Command 0x1821 - Show Image (Display Only)

No parameters.

End of any wrappers, at minimum including Response Message

If the request started successfully, the Request Status in the message wrapper is All Good, Requested Operation Was Successful.

Table - Request Example

Table - Response Example

Last updated