DE4424709A1 - Input=output control circuit for, e.g. SRAM, memory chip - Google Patents

Abstract

The control circuit is provided in a memory chip. The circuit includes lines for the chip address, data, and control, as well as the coupling lines of the circuit. These lines are directly linked to a microcontroller. The data processing is controlled by a stored program. Pref. the same circuit is used for different input and output modes, e.g. serial or parallel, according to the required use. The controller is distinguished in the same circuit between bit-serial and byte-parallel modes by a control pin.

Description

The invention relates to a circuit with which the input / output of user-specific memory chips can be.

For example, according to the current state of the art in the case of memory cards, the lines of the memory contained therein cherchips for addresses, data and control individually selected leads, generally with the interposition of protection circuits and the merging of these lines of Leave user circuit. The multitude of these lines (typically 30 ... 60) requires a not inconsiderable opening wall in the development and dimensioning of the fer term product.

In applications where absolute parallel processing is not absolutely necessary due to time constraints the use of a microcontroller the user-specific Relieve switching from standard tasks and the circuit reduce effort for the finished product. Furthermore the same circuit can differ depending on the program sequence support user circuits, such as serial or par  allele input / output with typical 4-6 or 16-18 Cables.

A simple da can be done without external circuitry transfer can be made when a buffered memory chermodule on the one hand for reading / loading to a printer port personal computer is connected and on the other hand after simply plugging it into another (small) computer Query / processing of this data is used.

The microcontroller takes over together with the control the lines of the memory chips also secure the data due to potential separation from the user scarf tung.

Fig. 1 shows a basic circuit for 8 SRAM chips each 8 × 128 KB and a known controller with 32 bidirectional port lines compared to Fig. 2, which shows a known circuit with integrated circuits according to the prior art.

The controller ( 11 ) controls the memory chips (in the example 8) directly via its port lines. Fig. 3 shows a circuit variant with connection of the data out line ( 8 ) to 4 address lines ( 17 ), as well as the known wiring of bus drivers ( 24 ) and or-gate ( 25 ).

The controller differs in the circuit shown between bit serial and byte parallel using the control pin X.

bit serial

Transmission of address / data through the clock and Data while the status line is the direction of transmission (Read / write) and end of transmission.  

byte-parallel

Transfer of address / data out through 8 bit output port, as well as 4 bit data input through input port, also 4 Output lines, 1 of which serves as the clock and 1 further line as in bit serial transmission Direction of transmission indicates or reset / end of Transmission.

Via the low power line ( 6 ), stopping the processor clock can reduce the current consumption to a minimum of a few microamps, even when the voltage is switched on. However, the restart requires a waiting time of typically 1 millisecond before the next transaction.

Reference list

1 master serial
2 masters in parallel
3 clock
4 data in / out
5 status
6 low line
7 data out / addresses
8 data in
9 control line
10 ID parallel / serial
11 slave controller
12 memory chips
13 chip enable
14 read
15 write
16 chip select
17 address lines
18 data lines
19 master
20 pullup resistor
21 data buffer
22 address buffer / decoder
23 Control bus buffer
24 bus drivers
25 AND gates

Claims (2)

1. Circuit for input / output control of memory chips, characterized in that

• - That the address / data and control lines of a memory chip and the connecting lines of the user circuit are basically connected directly to a microcontroller and the processing of the stored program is controlled.

2. Circuit for the input / output control of memory chips, characterized, that the same circuit for different applications Input / output forms (serial or parallel) can be used can.