Microcomputer with built-in serial input-output circuit and collision detection circuit responsive to common input-output line being occupied
AssigneesMitsubishi Electric Semiconductor Software Co., Ltd., Mitsubishi Denki Kabushiki Kaisha
InventorsMasahiro Asano, Kimikatsu Matsubara
Life of this patent
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Abstract
Even in the case where a microcomputer according to the present invention is directly connected to a bus in a LAN, it is possible to upgrade the data transfer speed of the LAN. When a built-in exclusive-OR circuit in the SIO of the microcomputer detects the discordance between a signal at an R.times.D terminal and a signal at a T.times.D terminal, a D flip-flop circuit generates and sends out an interrupt signal to the CPU. The CPU is made to recognize the collision of signals by the generation of the interrupt signal.
Claims6
A microcomputer having a built-in serial input-output circuit, an IO port and a CPU, said built-in serial input-output circuit and said IO port sharing a common input-output line for inputting and outputting data, said built-in serial input-output circuit comprising:
- a serial input-output means for converting parallel data into serial data and outputting said serial data to an output terminal and for converting serial data input from an input terminal into parallel data;
- a clock signal supply means for supplying a data transfer clock signal to said serial input-output means;
- and
- a collision detection circuit, activated in response to a control signal indicating that the common input-output line is occupied by said built-in serial input-output circuit, for comparing a first signal supplied to said output terminal with a second signal supplied to said input terminal and supplying an interrupt signal to said CPU when said first and second signals are in discordance.
Dependencies are inferred from the claim text.