Memory device alert of completion of internally self-timed power-up and reset operations
A memory device can include: a non-volatile storage register configured to store an active reset polling enable bit that corresponds to a reset operation; a controller configured to control execution of the reset operation on the memory device; an operation completion indicator configured to provide a reset recovery indication external to the memory device when the reset operation has completed and the active reset polling enable bit is set; and a command decoder configured to receive a command to be executed on the memory device in response to the reset recovery indication.
1. A memory device, comprising:
a) a non-volatile storage register configured to store an active reset polling enable bit that corresponds to a reset operation;
b) a reset control circuit coupled to the non-volatile storage register, and being configured to control execution of the reset operation on the memory device;
c) an output circuit configured to transition a signal on an output pin from a high impedance state to a first low impedance state in response to the reset operation being initiated on the memory device and the active reset polling enable bit being set;
d) an operation completion indicator configured to automatically output a reset recovery indication from the memory device when the reset operation has completed and the active reset polling enable bit is set, wherein the reset recovery indication comprises a transition of the signal on the output pin from the first low impedance state to a second low impedance state;
e) a command decoder configured to receive a command to be executed on the memory device in response to the reset recovery indication; and
f) a status register configured to be written to along with the reset recovery indication to indicate that the reset operation has completed execution on the memory device, wherein the status register is also configured to store the active reset polling enable bit.
2. The memory device of claim 1 , wherein the non-volatile storage register is configured to be programmed by matching a received opcode against a predetermined opcode.
3. The memory device of claim 1 , wherein the output circuit is configured to maintain the signal on the output pin in the second low impedance state while a chip select signal is asserted.
4. The memory device of claim 3 , wherein the output circuit is configured to transition the signal on the output pin from the second low impedance state to the high impedance state in response to the chip select signal being deasserted.
5. The memory device of claim 1 , further comprising a digital logic circuit configured to output a status bit from the status register to provide the reset recovery indication.
6. The memory device of claim 1 , wherein the reset operation comprises an exit from a power-down mode.
7. The memory device of claim 1 , wherein the reset operation comprises a power-up operation.
8. The memory device of claim 1 , wherein the operation completion indicator comprises a power-on reset circuit configured to detect whether an internal supply voltage is greater than a predetermined supply voltage level.
9. The memory device of claim 1 , wherein the reset control circuit is configured to copy the contents of the non-volatile storage register into the status register, wherein the status register is a volatile memory.
10. The memory device of claim 1 , further comprising a plurality of non-volatile storage registers, each having an active reset polling enable bit that corresponds to a different reset operation.
11. A memory system, comprising the memory device of claim 1 , and further comprising:
a) a host configured to receive the reset recovery indication from the memory device prior to a specified recovery time; and
b) a serial peripheral interface (SPI) coupled between the host and the memory device.
12. A method of controlling a memory device, the method comprising:
a) storing, in a non-volatile storage register, an active reset polling enable bit that corresponds to a reset operation;
b) controlling execution of the reset operation on the memory device;
c) transitioning, by an output circuit, a signal on an output pin from a high impedance state to a first low impedance state in response to the reset operation being initiated on the memory device and the active reset polling enable bit being set;
d) determining when the reset operation has completed on the memory device;
e) automatically outputting a reset recovery indication from the memory device when the reset operation has completed and the active reset polling enable bit is set, wherein the reset recovery indication comprises a transition of the signal on the output pin from the first low impedance state to a second low impedance state;
f) receiving, by a command decoder, a command to be executed on the memory device in response to the reset recovery indication; and
g) writing a status register along with the reset recovery indication to indicate that the reset operation has completed execution on the memory device, wherein the status register is also configured to store the active reset polling enable bit.
13. The method of claim 12 , further comprising programming the non-volatile storage register by matching a received opcode against a predetermined opcode.
14. The method of claim 12 , wherein the providing the reset recovery indication comprises maintaining the signal on the output pin of the memory device in the second low impedance state while a chip select signal is asserted, and transitioning the signal from the second low impedance state to the high impedance state in response to the chip select signal being deasserted.
15. The method of claim 12 , further comprising outputting a status bit from the status register to provide the reset recovery indication.
16. The method of claim 12 , wherein the reset operation comprises exiting from a power-down mode.
17. The method of claim 12 , wherein the reset operation comprises a power-up operation.
18. The method of claim 12 , wherein the determining when the reset operation has completed comprises detecting, by a power-on reset circuit, whether an internal supply voltage is greater than a predetermined supply voltage level.
19. The method of claim 12 , wherein the determining when the reset operation has completed comprises copying the contents of the non-volatile storage register into the status register, wherein the status register is a volatile memory.
20. The method of claim 12 , further comprising programming a plurality of non-volatile storage registers, each having an active reset polling enable bit that corresponds to a different reset operation.