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KX-PX1CX
4.6.
CPU Operation
4.6.1.
Explanations of the program operation of the Main CPU (IC3) (same with the CPU
on the IP board)
on the IP board)
The CPU has high-performance calculation capabilities and contains peripheral functions. You will understand the overview of
each function from the block diagram shown below.
This set moves the program from ROM to SDRAM in order not to degrade the CPU performance.Immediately after the power is
turned on, the CPU reads the program from the Flash ROM and writes it to the SDRAM. Afterward, the CPU executes the pro-
gram on the SDRAM.After that, the CPU accesses the Flash ROM only when saving various settings and histories. So, it does
not look like performing frequently even if you observe ROM bus signals.
This CPU is not designed specifically for this set. It is a general-purpose CPU and a high-performance CPU for multimedia use.
each function from the block diagram shown below.
This set moves the program from ROM to SDRAM in order not to degrade the CPU performance.Immediately after the power is
turned on, the CPU reads the program from the Flash ROM and writes it to the SDRAM. Afterward, the CPU executes the pro-
gram on the SDRAM.After that, the CPU accesses the Flash ROM only when saving various settings and histories. So, it does
not look like performing frequently even if you observe ROM bus signals.
This CPU is not designed specifically for this set. It is a general-purpose CPU and a high-performance CPU for multimedia use.
(Main board) Data transfer to the thermal head by CPU
Below is a simple explanation of a system to achieve the processing of a dye sublimation printer and the data transfer to the
thermal head using CPU.
The thermal head is a huge shift register. The ON/OFF signals of 1 and 0 are written to this register. Portions where 1s are writ-
ten generate heat. This heat generation heats the dye sublimation ink film and transfers the ink onto the paper. To heat a 1-line
printing portion on a dot-by-dot basis, rewriting of the register is controlled for 256 times dividedly.
The CPU makes the image data and heat corrections (corrections based on the temperature of the thermal head or the last heat
information) to decompose and rearrange the image data so that it meets the format of the shift register of the thermal head.
Although the amount of this processing is huge, the high-speed capability of the CPU (384MHz, 2 instructions/clock) enables
the processing in real time.
Data transfer to the thermal head is made periodically using the 2-dimension (2D) DMA transfer function inside the CPU.
thermal head using CPU.
The thermal head is a huge shift register. The ON/OFF signals of 1 and 0 are written to this register. Portions where 1s are writ-
ten generate heat. This heat generation heats the dye sublimation ink film and transfers the ink onto the paper. To heat a 1-line
printing portion on a dot-by-dot basis, rewriting of the register is controlled for 256 times dividedly.
The CPU makes the image data and heat corrections (corrections based on the temperature of the thermal head or the last heat
information) to decompose and rearrange the image data so that it meets the format of the shift register of the thermal head.
Although the amount of this processing is huge, the high-speed capability of the CPU (384MHz, 2 instructions/clock) enables
the processing in real time.
Data transfer to the thermal head is made periodically using the 2-dimension (2D) DMA transfer function inside the CPU.
(Main board) Communications between the CPU and the mechanical CPU
The main CPU interfaces to the mechanical CPU through the high-speed I2C and the low-speed UART (asynchronous serial)
channels. The UART is used for the initial programming of the mechanical CPU. (For details, refer to the “Initial programming of
the mechanical CPU” described separately.)
Below stated are major descriptions of the communications through the I2C interface.
channels. The UART is used for the initial programming of the mechanical CPU. (For details, refer to the “Initial programming of
the mechanical CPU” described separately.)
Below stated are major descriptions of the communications through the I2C interface.
1. Mutual recognition
Recognition jobs including the checking whether the other side is working normally.
2. Synchronization of the printing operation
The mechanical CPU drives the motor and monitors the sensors. The main CPU produces the printing data output to the ther-
mal head. The both execute the printing operation by synchronizing with each other.
mal head. The both execute the printing operation by synchronizing with each other.
(Main board) USB interface of the CPU
The CPU has USB circuits (Full speed) built-in. Each of USB-Host 1ch and USB-Function 1ch works independently. The USB
connector on the front of the set supports the PictBridge standard based on the USB-Host function. The outline of the PictBridge
standard: it is the USB-IF standard developed in 2003 aimed to make direct printing mainly from digital still cameras.
The USB-Function makes communications by linking to the USB-Host of the CPU on the IP board (the same CPU) inside the
set.
connector on the front of the set supports the PictBridge standard based on the USB-Host function. The outline of the PictBridge
standard: it is the USB-IF standard developed in 2003 aimed to make direct printing mainly from digital still cameras.
The USB-Function makes communications by linking to the USB-Host of the CPU on the IP board (the same CPU) inside the
set.
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