JPS59170933A - Input data control device of printer - Google Patents

Abstract

PURPOSE:To sample one bit every time-up and to restart a timer repeatedly by outputting a busy signal immediately at the input of the data from a host computer and starting a timer by an interruption. CONSTITUTION:When the data are inputted from the host computer 1, an interruption is applied to a terminal INT0 of a CPU4 at the rise of a start bit of the data and the CPU4 outputs a busy signal from a terminal P31 and sets up time t2 to a timer 8 to start the timer. When the timer 8 counts up the time t2 and times up, an interruption is applied to a terminal INT1 of the CPU4 and the CPU4 checks whether the start bit is inputted or not, and when the start bit is inputted, sets up the timer 8 to the time t1 of the sample mode to start the timer 8. If the start bit is not inputted, the CPU4 checks a stop bit, and in case of the input of the stop bit, transfers 8-bit data to a buffer in a RAM6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an input data control device for a printer that is connected to a host computer and receives serially transmitted data from the host computer to control printing.

[Technical background of the invention and its problems]

Conventionally, this type of printer sequentially transmits data serially transmitted from a host computer to an interface element.
The data is input bit by bit, and when all 8 bits are present, the interface element interrupts the CPU (Central Processing Unit) and outputs the data.
A host computer heavy signal was output from U through I- through the Intern Ace element.

Therefore, it takes a long time for the host computer to confirm the busy signal after receiving the data tB'r.Therefore, there is a problem in that the host computer is monopolized during that time. Furthermore, since interfaces and elements are required, the mounting area of the circuit on the PC board is large, and there is a problem in that the cost is high.

[Purpose of the invention]

This invention was made to solve these problems, and is capable of immediately outputting a busy signal in response to an input from a host computer or central device, and moreover, It is an object of the present invention to provide an input data control device for a printer that does not require circuits, can reduce the mounting area of circuits on a PC board, and can reduce costs.

[Summary of invention].

This invention immediately outputs a busy signal to the host computer at the rising edge of the data bit transmitted from the host computer, starts a timer by an interrupt, and every time the timer times up thereafter. It samples the data one bit at a time, restarts the two-note timer repeatedly, and when a stop bit is input, controls the transfer of the sampled data to the buffer for printing.

[Example of explanation] Huangshita explains the wheat embodiment of this invention with reference to the drawings:
In the figure, 1 is a host computer, 2 is a printer, and both are connected to each other via a transmission line 3.

I'm here. The printer 2 includes a CPU'U (central processing unit) 4, a ROM (read/write memory) 5, and an RA.
M (random access memory) 6, printing mechanism 71
．． A timer 8 etc. is provided.

The CPU 4 has 'ROMj5. Each part is controlled based on the zologram data stored in the host computer 1, and data from the host computer 1 is inputted to the P3φ terminal for data input via the output circuit 9 and the inverter 10. In addition, the CPU 4 inputs the busy signal from the P31 terminal for signal output via the 74277 circuit 11 to the IN'Tφ terminal for interrupt input through the 74277 circuit 11. host computer 1
It is output to. The CPtJ4 also controls the timer 8 and inputs the time-up signal of the timer 8 to the IN and T1 terminals for interrupt input. Furthermore, the CPU 4 controls the RAM and 6 to perform data storage processing, and also controls the output of mark and hand data to the printing mechanism 7 via the interface 12.

2 to 5 show the input data of the CPU 4.

This is a flowchart showing control, and data control will be described below based on this flowchart.

When data is input from the host computer 1, an interrupt is generated at the INTφ terminal of the CPtT4 at the rising edge of the start bit of the data, and the CPU 4 performs the processing shown in FIG. That is, it outputs a busy signal from the P31 terminal and recognizes the start bit in the timer 8. Set the waiting time t2 and start. This time t2 is the time required to read one bit.

It is set at about half capacity and sipped. Timer 8 is 1.2 o'clock.

When the time is up, C'PU4 (r4I
When an interrupt is received on the NTI terminal, the CPU 4 performs the processing shown in FIG. - Set the time t of the mode and start. This time t is equal to the time required to read and absorb one bit, and is set to approximately twice 1□.If the start bit has not been input yet, the stop bit is checked and the .

Lai. If there is an input of 8 or 8 as shown in Figure 5,
Transfer the data of Pitt to the buffer of R, AM4,
conduct. If there is no start or stop bit yet, read one bit as data and store the data in RA and M6.

In the embodiment of the present invention having such a configuration, it is possible to perform Zolit control by converting the real data from the medium-sized computer 1 to parallel data without using an interface element. 4. Reduce the mounting area on the board. ＜Can be done, and costs can be reduced. Also, the rising edge of the start bit in the data start signal.

Since the CPU 4 is interrupted and a busy signal is immediately output from the CPU 4 to the host computer 1, the host computer 1 can immediately perform other processing after confirming the busy signal, and the host computer 1 can no longer operate. rate can be improved.

〔Effect of the invention〕

As described above, according to the present invention, a busy signal can be immediately output in response to data input from a host computer, and an interface element is not required, thereby reducing the mounting area on a PC board and reducing costs. It is possible to provide a data control device.

[Brief explanation of drawings]

The figures show an embodiment of this invention, and Figure 1 is! Tip 2
Figure 2 is a flowchart showing interrupt processing using a start bit, Figure 3 is a flowchart showing timer interrupt processing, and Figure 4 is a flowchart showing timer interrupt processing.
The figure is a flowchart showing start processing, and FIG. 5 is a flowchart showing stop processing. 1... host computer, 2... printer, 4...
...CPU (central processing unit), 5...ROM (
6... RAM (random access memory), 7... Printing mechanism, 8... Timer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In a printer that is connected to a host computer and receives serially transmitted data from the host computer to control printing, the host computer outputs the heavy signal at the rising edge of the data start bit and starts a timer by interrupting the printer. The above data is buzzed one by one until the stop bit is input, and when the stop bit is input, the data is buzz-pulled. An input data control device for a printer, comprising: means for controlling transfer of data to a buffer for printing.