KR940009745B1 - Pc interfacing circuit - Google Patents

Abstract

The MIDI interface circuit for PC supports 128 MIDI channels controlling multiple electronic musical instruments or sound source modules with General MIDI specification. The circuit comprises multiple coprocessors (62,63) controlling overall operations of the interface; memories (64-1 - 64-8) holding MIDI channel message; S/P, P/S converters (65-1 - 65-8) converting data between MIDI interface circuit and electronic musical instruments; latches (56-59) holding data between PC and MIDI interface; PC interface, interrupt, coprocessor control circuits.

Description

MIDI interface circuit for PC

1 is a conventional one port MIDI interface circuit diagram.

2 is a MIDI interface circuit diagram of the present invention.

3 is a main control flowchart according to the mode of the MIDI interface circuit.

4 is a control flowchart of record processing.

5 is a process control flow chart of the play mode.

6 is a flowchart of a record timer interrupt service routine.

7 is a flowchart of a fly timer interrupt processing routine.

8 is a process flow diagram of an EBH instruction in accordance with the present invention.

Table 1 shows the input / output address table of the interface circuit.

Table 2 is a command table for 8 port control.

* Explanation of symbols for main parts of the drawings

50: PC bus 51,52: deep switch

53: I / O address selector 54: Interrupt control

55: PC interface control unit 56-59: latch

60, 61: co-processor control unit 62, 63: co-processor

64-1 to 64-8: Memory sections 65-1 to 65-8: S / P and P / S converters

66-1 to 66-8: MIDI circuit

The present invention relates to electronic musical instruments. In particular, when controlling a newly released general midi electronic musical instrument or sound module using a PC (PC) by supporting 128 MIDI channels at the same time It's about a MIDI interface circuit for PCs that is suitable for working with musical instruments.

In order to compose and arrange music using a computer, an interface circuit for converting PC information to MIDI information or MIDI information to PC information is essential. A device for storing, editing, and outputting MIDI information input through this interface circuit is commonly referred to as sequencer software.

Conventional electronic instruments can output only one specific tone per instrument at the same time, but the electronic instrument or sound source module manufactured according to the newly established general MIDI standard is designed to output 16 tones simultaneously.

Since each timbre should be assigned a different MIDI channel, only one sound source module can be controlled simultaneously with the conventional single port interface circuit. This is because the MIDI standard consists of 16 MIDI channels, so if one MIDI channel is assigned to each voice, only 16 voices can be controlled.

1 is a configuration diagram of a one-port MIDI interface circuit that is generally used. As shown in FIG. 1, the reference address is set according to the state of the deep switch 3, and the MIDI interface circuit and the PC are connected according to the input address signal. Writing and reading data between the PC and the co-processor 8 described below, and an I / O address selection section 2 for selectively outputting data, commands, and status signals via the data bus. PC interface control unit 4 for controlling the PC, latches (5, 6) for temporarily storing data transmitted and received between the PC bus and the co-processor (8), and controls the function of the electronic instrument according to the command transmitted from the PC A co-processor 8 for setting various modes and performing various controls, a co-processor control unit 7 for controlling the functions of the co-processor 8, and peripheral MIDI circuits ( 11) and S / P and P for converting serial data in parallel and serial data in parallel for data transmitted / received between the memory unit 9 for storing data from the PC, and the peripheral MIDI circuit 11 and the interface circuit. / S conversion section 10.

The operation and problems of the conventional MIDI interface circuit configured as described above will be described in detail as follows.

First, the information exchange between the 1-port MIDI interface circuit and the PC is largely divided into two as shown in Table 1.

Input / output of data is performed at the address of base address + 0 in the I / O address, and information of status in and command out is exchanged at base address +1. .

Here, the base address can be converted according to the adjustment of the dip switch 3 attached to the I / O address selector 2 for the I / O address selection.

On the other hand, the information of the status Inn transmitted from the MIDI interface circuit to the PC bus at the base address + 1 is information indicating whether the co-processor 8 can receive information from the PC or information to be transmitted to the PC bus. Data that tells if there is a

The PC looks at the status of the register holding the status in and sends information to the co-processor 8 or inputs information from the co-processor 8.

The command information output from the PC to the co-processor 8 via the I / O address of the base address + 1 sets the co-processor 8 to a desired mode among various modes. The co-processor 8 performs various modes of operation such as recording mode, performance mode, simultaneous recording mode, metronome on / off, and tempo adjustment.

If you are in the current recording mode, the MIDI channel message will come through the interface circuit through the external electronic instrument. Since the MIDI message is transmitted at a transmission rate of 31.25 Kbps, the interface circuit converts this serial information into parallel information and inputs it to the memory section 9. The co-processor 8 compares the last addressed memory address pointer with the current address pointer, and if there is data to be processed, signals that there is information to be sent to the PC through the I / O address of the base address + 1, the status in register. (Not shown) and transmits MIDI information to I / O address of base +0.

The co-processor 8 then calculates the time difference from the last transmitted MIDI data event and sends it together.

In the case of the performance mode, the PC notifies the co-processor 8 in the form of a command to switch to the performance mode in the reverse of the recording procedure, and the co-processor 8 requests a MIDI event of the track.

Upon receiving this request, the PC program immediately gives the MIDI event and its dispatched time as the I / O address of the data output, and the co-processor 8 outputs the MIDI event after this time to an external electronic instrument.

However, such a conventional MIDI interface circuit can only use 16 channels set in the MIDI standard. Recently, the electronic musical instrument or sound source module can output 16 voices at the same time. In order to control with an external sequencer, it is necessary to allocate one Miti channel for each voice.

Therefore, the existing 1-port MIDI interface cannot control more than one general MIDI standard electronic instrument at the same time. To solve this problem, more general interface circuits are necessary, which uses 16 MIDI channels per port. The channel is increased to the number of ports x 16.

Accordingly, the present invention can control a plurality of instruments conforming to the general MIDI standard for channels constituting each port by allocating a plurality of ports to a plurality of co-processors in view of the above-mentioned defects in the conventional MIDI interface circuit. It is an object of the present invention to provide a means which can be described in detail below with reference to the accompanying drawings.

2 is a block diagram of the MIDI interface circuit of the present invention, as shown therein, an I / O address selector 53 for designating an input / output address according to the type of data transmitted and received between the PC and other MIDI interface circuits; Memory units 64-1 to 64-8 for storing MIDI channel messages input from an external electronic instrument, and S / P and P / S converters for converting serial data and parallel data into parallel data and serial data and outputting the same. (65-1 to 65-8) and control commands from PCs to perform the set mode operation such as recording, performance, and tempo, output MIDI events to external electronic instruments, and input from external electronic instruments. Co-processors 62 and 63 for inputting a MIDI channel message to the PC through the memory units 64-1 to 64-8 and controlling the overall operation of the interface circuit, and the co-processors 62 and 63; ) And PC Latches 56 to 59 for temporarily storing the data to be exchanged, PC interface controller 55 for controlling the latches 56 to 59 according to input and output control commands from the PC, and control of the interface controller 55. And the co-processor controllers 60 and 61 for controlling data input / output of the latches 56 to 59 and the memory units 64-1 to 64-8.

In the above configuration, the expansion to eight MIDI ports can support a total of 128 MIDI channels, which means that eight instruments of the general MIDI standard can be managed.

As the number of MIDI ports to be processed simultaneously is expanded eight times, the co-processors 62 and 63 are increased by two, and four MIDI ports are managed. Since the two co-processors 62 and 63 must exchange PC and information without colliding with each other, the two co-processors 62 and 63 sequentially process using the HOLD / ACK signal terminal. Since data is input at one time through eight MIDI hardware, each co-processor (62, 63) can time-multiplex the events input at four MIDI terminals to the corresponding memory (64-1 to 64-8). On the contrary, in order to output the data of the PC to the outside, each co-processor (62, 63) switches the four MIDI ports in order to output to the outside.

Referring to the circuit and operation and effect of the present invention configured as described above in detail as follows.

The command “EBH” in Table 2 is used to select and cancel eight independent MIDI ports. The command "EBH" entails two operand vials, with the lower four bits of each operand enabling or disabling eight ports.

The program of co-processors 62 and 63 will set or reset the bits of the port active register by the " EBH " command as in flow eighth. The first four bits of the first operand of the command "EBH" are the message ID, which identifies which track the MIDI event that is output to the outside at the time of the play operation is.

For example, if you play Fly Track 0, activate eight ports, and record MIDI events coming into all ports, the command from PC to co-processors (62, 63) is "EBH", Operands are "OFH", "OFH".

The main routine is shown in Figure 3, which executes each sub-routine when in record or play mode.

4 is a flow chart of the record routine. If the record mode of the corresponding port is on, it checks whether the main pointer and the chase pointer match, and if it matches, shifts the data in the record mode determination register to search all 8 ports. If the main pointer and the chase pointer do not coincide with each other, the main event and the value of the timer X are sent to the PC using a data-in register, and then the value of the timer X is reset and the chase pointer is increased. Repeat the pointer comparison process.

On the other hand, Figure 5 is a flow chart for the control mode for the fly mode, if the fly mode of the corresponding port is turned on, the value of the timer Y is examined and if the value is 0, the memory unit 64-1 to 64-8 using the fly pointer. It outputs a MIDI event of, and checks the play mode for all ports by shifting the play determination register if the play mode for that port is off.

6 and 7 are flow charts of a record timer interrupt service routine and an interrupt service routine of a play timer, wherein values of timer X and timer Y managing record time and play time when record mode or play mode are turned on, respectively. Records MIDI events for all ports while reducing or outputs MIDI events through the active port.

The record or play mode is determined by the record and play commands from the PC. When entering normal record or play mode, timer X, which manages the time of the record, and timer Y, which manages the time of the play, are activated.

In the case of record, when MIDI event is input, the value of timer X corresponding to the input port is increased. In case of play, when the value of timer Y is decreased by receiving MIDI event and timer value from PC, the value is reduced to 0. Outputs MIDI events to the port and requests the next MIDI event to PC.

Co-processor 62 manages ports 64-1 to 64-4, and co-processor 63 manages ports 64-5 to 64-8, so the PC interface circuit of FIG. Co-processors (62, 63) and PC bus (50) is connected to the address exchange information, the base +2 using the address of the co-processor 63 and PC bus 50 is connected.

When each of the co-processors 62 and 63 wants to send information to the PC, it is informed that there is data to output through the interrupt terminal of the PC. The interrupt control unit 54 of FIG. Inputs the signal of interrupt request terminal of (63) to PPC.

Accordingly, the present invention enables simultaneous control of up to eight general MIDI electronic instruments on the market.

As described above, the present invention enables to implement an interface circuit of an instrument in which a plurality of tones are output from one instrument, and many MIDI channels are required.

Claims (1)

Signals to transmit or receive information between PC and MIDI interface circuits, and I / O addresses for data in various modes such as recording, performance, and tempo adjustment, as well as addresses for selectively specifying data input / output functions. An I / O address selector 53 to be generated, memory units 64-1 to 64-8 for storing channel messages inputted from an external electronic instrument to the MIDI interface circuit and converted into parallel data, and from an external electronic instrument S / P and P / S converters (65-1 to 65-8) for converting serial data into parallel data, inputting them into a MIDI interface circuit, and converting parallel data of the MIDI interface circuit into serial data and outputting them to an external electronic instrument. And control commands from the PC to perform recording, performance and tempo settings, and output mini events to the external electronic blocker. Co-processors (62, 63) for inputting the MIDI channel message from an external electronic instrument to transmit to the PC through the memory unit (64-1 to 64-8) and control the overall operation of the interface circuit; A latch 56-59 for temporarily storing data exchanged between the co-processors 62 and 63 and the PC interface controller 55 for controlling the latch 56-59 according to an input / output control command from the PC. And an interrupt controller 54 which interrupts the PC and generates a control signal to transmit information from the co-processors 62 and 63 to the PC, and the latch according to the control of the PC interface unit 55. 56-59) and a co-processor control unit (60, 61) for controlling data input / output of the memory units 64-1 to 64-8.