Control methods and memory systems using the same

Patent metadata

Field	Value
Publication number	US-9627031-B1
Application number	US-201615067377-A
Country	US
Kind code	B1
Filing date	Mar 11, 2016
Priority date	Mar 11, 2016
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A control method for a memory system is provided. A memory controller of the memory system is configured to control the memory device. After a condition is met, the memory controller performs a retry operation to compensate for shifting of a data strobe signal sent from the memory device until the memory system enters a normal operation mode. When the shifting of the data strobe signal is compensated for, the number of pulses of the data strobe signal in the gating window is equal to the first predetermined number.

First claim

What is claimed is:

1. A control method for a memory system, comprising: after a condition is met, performing a retry operation until the memory system enters a normal operation mode;
wherein the retry operation comprises:
defining a predetermined gating window having an initial starting time point;
performing a first dummy read operation on a memory device of the memory system by sending at least one first read command to the memory device and generating a data strobe signal by the memory device in response to the at least one first read command;
determining whether a number of pulses of the data strobe signal in the gating window having the initial starting time point is equal to a first predetermined number; and
when it is determined that the number of pulses of the data strobe signal in the gating window having the initial starting time point is not equal to the first predetermined number, shifting the gating window by moving a starting time point of the gating window from the initial starting time point to a first shifted starting time point.

2. The control method as claimed in claim 1 , wherein when the memory system exists a suspend mode, the condition is met.

3. The control method as claimed in claim 1 , wherein when an operation frequency of the memory system changes from a first frequency to a second frequency, which is different from the first frequency, the condition is met.

4. The control method as claimed in claim 1 , wherein the predetermined gating window having the initial starting time point is a gating window which is used for a read operation performed when the memory system is at the normal operation mode last time.

5. The control method as claimed in claim 1 , wherein the predetermined gating window has a fixed time length.

6. The control method as claimed in claim 1 , wherein the step of determining whether the number of pulses of the data strobe signal in the gating window is equal to the first predetermined number:
determining whether a number of rising edges of the data strobe signal in the gating window is equal to a second predetermined number; and
determining whether a number of falling edges of the data strobe signal in the gating window is equal to a third predetermined number,
wherein when the number of rising edges of the data strobe signal in the gating window is not equal to the second predetermined number or when the number of falling edges of the data strobe signal in the gating window is not equal to the third predetermined number, it is determined that the number of pulses of the data strobe signal in the gating window is not equal to the first predetermined number.

7. The control method as claimed in claim 1 , wherein the retry operation further comprises:
performing a second dummy read operation on the memory device by sending at least one second read command to the memory device and generating the data strobe signal by the memory device in response to the at least one second read command;
determining whether the number of pulses of the data strobe signal in the gating window having the first shifted starting time point is equal to the first predetermined number; and
when it is determined that the number of pulses of the data strobe signal in the gating window having the first shifted starting time point is not equal to the first predetermined number, shifting the gating window by moving the starting time point of the gating window to a second shifted starting time point,
wherein the initial starting time point is between the first shifted starting time point and the second shifted starting time point.

8. The control method as claimed in claim 7 , wherein the retry operation further comprises:
when it is determined that the number of pulses of the data strobe signal in the gating window having the first shifted starting time point is equal to the first predetermined number, shifting the gating window by moving the starting time point of the gating window to a third shifted starting time point,
wherein the third shifted starting time point is between the initial starting time point and the first shifted starting time point, and
wherein when the memory system enters the normal operation mode and performs a read operation at the normal operation mode, the memory system latches data from the memory device based on the gating window which starts at the third shifted starting time point.

9. The control method as claimed in claim 7 , wherein the retry operation further comprises:
performing a third dummy read operation on the memory device by sending at least one third read command to the memory device and generating the data strobe signal by the memory device in response to the at least one third read command;
determining whether the number of pulses of the data strobe signal in the gating window having the second shifted starting time is equal to the first predetermined number;
when it is determined that the number of pulses of the data strobe signal in the gating window having the second shifted starting time is not equal to the first predetermined number, determining whether the retry operation ends; and
when it is determined that the retry operation does not end, shifting the gating window by moving the starting time point of the gating window to a third shifted starting time point,
wherein the third shifted starting time point is between the initial shifted starting time point and the first shifted starting time point.

10. The control method as claimed in claim 9 , wherein the retry operation further comprises:
when it is determined that the retry operation ends, issuing an interrupt to indicate that compensation for shifting of the data strobe signal is unsuccessful.

11. The control method as claimed in claim 10 ,
wherein when an operation speed of the memory system is larger than a speed threshold, it is determined that the retry operation does not end, and
wherein when the operation speed of the memory system is not larger than the speed threshold, it is determined that the retry operation ends.

12. The control method as claimed in claim 9 , wherein the retry operation further comprises:
when it is determined that the number of pulses of the data strobe signal in the gating window having the second shifted starting time point is equal to the first predetermined number, shifting the gating window by moving the starting time point of the gating window to a fourth shifted starting time point,
wherein the fourth shifted starting time point is between the initial starting time point and the second shifted starting time point, and
wherein when the memory system enters the normal operation mode and performs a read operation at the normal operation mode, the memory system latches data from the memory device based on the gating window which starts at the fourth shifted starting time point.

13. The control method as claimed in claim 9 , wherein the retry operation further comprises:
performing a fourth dummy read operation on the memory device by sending at least one fourth read command to the memory device and generating the data strobe signal by the memory device in response to the at least one fourth read command;
determining whether the number of pulses of the data strobe signal in the gating window having the third shifted starting time point is equal to the first predetermined number; and
when it is determined that the number of pulses of the data strobe signal in the gating window having the third shifted starting time point is not equal to the first predetermined number, shifting the gating window by moving the starting time point of the gating window to a fourth shifted starting tim

Assignees

• Mediatek Inc

Inventors

• Chen Kai-Hsin
• Lin Shih-Hsiu

Classifications

• G11C11/409

  Read-write [R-W] circuits · CPC title

• G11C7/1045

  Read-write mode select circuits · CPC title

• G11C7/227

  Timing of memory operations based on dummy memory elements or replica circuits · CPC title

• G11C7/22

  Read-write [R-W] timing or clocking circuits; Read-write [R-W] control signal generators or management · CPC title

• G11C8/04

  using a sequential addressing device, e.g. shift register, counter · CPC title