Other

Mitsubishi Denki Kabushiki Kaisha

Renesas Technology Corp.

Toshihiro Sezaki

Hiroyuki Kimura

Katsunobu Hongo

Kunio Tani

Tsutomu Tanaka

Tomohisa Iba

Tetsu Tashiro

Mikio Kamiya

Makoto Yamamoto

Masato Koura

Yasuhiro Ami

A microcomputer with a built-in non-volatile semiconductor memory, which can automatically perform a work of temporarily interrupting automatic writing or automatic erase and accepting an interruption process when an interruption occurs during the automatic writing or automatic erase by using an interrupt request signal for a microcomputer as an external input for controlling automatic writing or automatic erase of a flash memory.

Microcomputer having a flush memory that can be temporarily interrupted during an erase process

A microcomputer with a built-in flash memory includes a flash controller for controlling writing/erasing of the flash memory in accordance with a command from a CPU. The flash controller produces a CPU rewriting mode designating signal and a busy signal during writing/erasing of the flash memory. In response to the two signals, awaiting mode controller implements a waiting mode by outputting a control signal to open and close an AND gate using the control signal, thereby halting a supply of a clock signal to the CPU in the waiting mode. The microcomputer can reduce the load on software for writing/erasing of the flash memory, and the load on developing software.

Flash memory access control via clock and interrupt management

A microcomputer comprises: a flash memory for storing rewriting control F/W and user S/F; a command register for specifying content of rewriting control; a address register to be subjected to rewriting-control; a data register for specifying data to be written; a power-supply pump circuit in the flash memory; and a control signal register for specifying/outputting a control signal to a memory decoder. A CPU of the microcomputer is capable of accessing these four registers to perform writing or reading. A given bit of the control signal register corresponds to a given control signal. A value written to the register becomes a control signal that will be directly supplied to both of the power supply circuit and the memory decoder, in the flash memory, to control them. By rewriting a set value of this control signal register using the rewriting control F/W according to a specified sequence, processing such as &ldquo;erase&rdquo; and &ldquo;program&rdquo; of the flash memory is performed. As a result, a layout area of an automatic sequence circuit is decreased, and a change in a sequence is also facilitated.

Microcomputer with built-in programmable nonvolatile memory

A nonvolatile semiconductor memory includes a memory block composed of a memory array having a plurality of memory cells arranged in a matrix form, each of the memory cells being composed of a nonvolatile transistor; a memory decoder necessary for erasing/writing/reading data of the nonvolatile transistor in the memory array; a charge pump necessary for erasing/writing/reading the data of the nonvolatile transistor in the memory array; a register having each of a plurality of control signals for controlling the memory decoder and the charge pump allocated to register 1 bit; and an updating device for updating a content of the register by a data processor coupled to the register. By using this updating device to update the content of the register, the memory decoder and the charge pump are controlled, the data of the memory block is erased, and data is written in/read from the nonvolatile transistor. Thus a selecting device other than a laser can be applied for suppressing the increase of an LSI circuit size in the same chip as that for a dedicated control circuit, verifying the disconnected state of a FUSE circuit in the memory, and trimming the FUSE circuit.

Nonvolatile semiconductor memory and automatic erasing/writing method thereof

Growing community of inventors

Tokyo, Japan

Toshihiro Sezaki