Printer with loudspeaker interface
View Patent ↗A printer includes a loudspeaker that announces error messages and the like. The error messages are stored as sound files in an onboard memory device. A central processor communicates with a speaker interface circuit by means of a data bus. A DMA controller is provided that mediates the transfer of instructions from the processor to the speaker interface and to a number of functional circuits that are also coupled to the bus. The speaker interface is equipped with a FIFO circuit that is responsive to DMA controller mediated transfer of sound files from the memory. In order to initiate the playing of a sound file the processor simply programs a DMA channel of the speaker interface.
1. A printer including:
a processor coupled to a data bus;
a memory device coupled to the data bus;
a number of functional circuit modules coupled to the data bus to receive instructions from the processor and data from the memory; and
a DMA controller arranged to mediate transfer of instructions from the processor to each of said number of circuits;
wherein the functional circuit modules include:
an image data expansion and decoding circuit;
a print data generation circuit for generating print data from the expanded and decoded image data circuit;
a printhead interface circuit configured to communicate data between the data bus and a micro-electromechanical pagewidth printhead; and
a speaker interface circuit that includes a FIFO circuit for DMA controller mediated transfers of sound files from the memory, the processor being configured to output a sound file to the speaker interface by programming a DMA channel of the speaker interface.
2. A printer according to claim 1 , wherein the speaker interface circuit includes a digital-to-analog converter of digital sound data from the memory into an analog signal.
3. A printer according to claim 2 , including an amplifier responsive to the output of the digital-to-analog converter.
4. A printer according to claim 3 , including a speaker coupled to an output side of the amplifier.
5. A printer according to claim 1 , wherein the speaker interface is clocked at the frequency of the sound files.
6. A printer according to claim 1 , wherein the FIFO is arranged to output a zero value when it is empty.