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CUnet master IC 3.3 V (5 V tolerant)

The MKY43 is a CUnet MEM mode (master/slave) IC. If it is connected to a CPU using an 8-bit or 16-bit bus, it can be accessed from the CPU. As a MEM mode IC, an MKY43 can be used as either a master or a slave terminal on a CUnet network. The MKY43 includes 512 bytes of shared memory, a buffer for its mail function, and a communication control register.

[512 bytes of shared memory]

The 512-byte shared memory consists of 64 blocks (8 bytes per block). This 512-byte shared memory is composed of a "self-owned area" to which only the CPU connected to itself (CUnet IC) can write, and an area where input data from other CUnet ICs is copied.
The number of blocks to use (self-owned area) can be specified for MKY43.
All of the data written by itself and input data from other CUnet ICs are applied to its 512-byte shared memory.
This means that the CPU easily grasps the state of the whole CUnet network simply by reading the shared memory of the CUnet IC connected thereto.

[Mail function buffer]

The mail function buffer consists of 2 receiving buffers and 1 send buffer. Each buffer is 256 bytes.
Process completion can be identified by detecting the send complete flag and the receive complete flag.

[Communication control register]

This register controls communication, including communication start, error checking, mail sending and receiving, etc. CUnet communication can be controlled easily just by accessing this register. The MKY43 also has 2 interrupt pins. It has a variety of interrupt functions including a shared memory-update interrupt, a mail-send interrupt, a mail receive-complete interrupt, a specific terminal-participation interrupt, a specific terminal-release interrupt, and a communication-error interrupt.

In addition to this wealth of interrupt function, the MKY43 also contains built-in communication protocol, allowing it to relieve the load on the CPU for communication functions.

[Differences between the MKY43 and the MKY40 (MEM mode)]

The MKY43 was developed to inherit the functions of the CUnet MKY40 (MEM mode, 5 V). The MKY43 works and functions just like the MKY40, but please observe the following practical differences in its use.


Differences between MKY43 and MKY40 (MEM mode)

Model MKY43 MKY40
Power supply voltage 3.3 V 5.0 V
Package 0.5-mm pitch 64 pins TQFP 0.5-mm pitch 100 pins TQFP
Bus pin level 3.3 V TTL (5 V tolerant)
(5.0 V TTL level CPU bus can be connected.)
5 V TTL level
(It is possible to connect only the 5.0 V system TTL level CPU bus.)
Bus width 16 bits / 8 bits 32 bits / 16 bits / 8 bits
Byte write when 16-bit user bus is connected Byte write is not supported (for write access).
(Set both #WRH pin and #WRL pin Low.)
Byte write is supported.
Interrupt pin #INT0, #INT1 #INT0, #INT1, #INT2
Port Out bit of SSR
Care Pulse bit of BCR
Not provided PO0, PO1, PO2, PO3 (SSR) CP (BCR)
Setting pin for address, etc.
(Initial value of BCR is written)
Not provided #SA0 to #SA5, #OWN0 to #OWN5, BPS0, BPS1
IO mode function Not provided Provided (The MODE pin is provided.)
CYCT output, PING output
(CYCT is equivalent to STB)
#CYCT signal and #PING signal can be output to UTY1 pin and UTY2 pin. #STB signal and PING signal are output
to #STB pin and PING pin respectively
(UTility pin Control Register)
Added for controlling UTY1 pin and UTY2 pin.
(Set this register by selecting from among Hi-Z, #CYCT output, and #PING output.)
Driving clock Clock input to the Xi pin
(The oscillator is not supported.)
Clock input to the Xi pin.
Or the crystal oscillator between the Xi pin and Xo pin can be supported.
TXD pin output
during reset period
Low level Clock frequency obtained by
dividing the driving clock by 32
Hazard protection Hazard-protection-buffer method Window-lock method
Memory map Different from that of the MKY40 -------
Address of each register Different from that of the MKY40 -------
Bus access time TRD (max) 89 ns TRD (max) 130 ns
Operating current (max) 75 mA 130 mA


MKY43 specifications

Bus width 8 bits / 16 bits
Control pin CS, RD, WRL, WRH
Interrupt pin 2 pins
Supported CPU voltage 3.3 V (5 V tolerant)
Communication method CUnet communication
Communication rate 3/6/12 Mbps (half duplex)
Package TQFP 64-pin
Package dimensions 12×12×1.2 mm (0.5 mm pitch)
Operating ambient temperature -40 to +85°C
Supply voltage 3.3 V
External input operating frequency 48 MHz

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