Method for transferring data on a memory card in synchonism with a rise edge and a fall edge of a clock signal
A method of controlling a storage device attached to a host device, includes transferring data with respect to the host device in synchronism with a rise edge and a fall edge of a clock signal in first and second transfer modes. In response to a check function command, status data indicating that the storage device supports the second transfer mode is output through a data terminal. In response to a set function command, the storage device is set into the second transfer mode. The check function and the set function are switched in response to a first value and a second value of a mode bit in the check function command.
1. A method of controlling a storage device including a command terminal; a plurality of data terminals; a clock terminal; a power terminal for a power supply voltage; a ground terminal for a ground voltage; and a nonvolatile memory,
the method comprising:
receiving a clock signal through the clock terminal from an outside of the storage device;
latching data received through at least one of the data terminals from the outside of the storage device, in accordance with only one of a rising edge and a falling edge of the clock signal, in a first transfer mode;
latching data received through at least one of the data terminals from the outside of the storage device, in accordance with both the rising edge and the falling edge of the clock signal, in a second transfer mode;
receiving a first command of a check function whose mode bit being a first value through the command terminal;
outputting first status data that includes information indicating that the storage device supports the second transfer mode, through one of the data terminals to the outside of the storage device, in response to the first command of the check function whose the mode bit being the first value;
receiving a first command of a set function whose the mode bit being a second value through the command terminal from the outside of the storage device;
setting the storage device into the second transfer mode in response to the first command of the set function whose the mode bit being the second value; and
switching the check function and the set function in response to the first value and the second value of the mode bit in the first command.
2. The method according to claim 1 , wherein the first value and the second value of the mode bit in the first command respectively determines the check function and the set function.
3. The method according to claim 1 , further comprising writing data received through at least one of the data terminals into the nonvolatile memory.
4. The method according to claim 1 , further comprising outputting second status data that includes information indicating that the storage device is set into the second transfer mode, through one of the data terminals to the outside of the storage device, in response to the first command of the set function whose the mode bit being the second value.
5. The method according to claim 1 , wherein:
the first status data includes data fields of a plurality of function groups; and
the second transfer mode is assigned to one of the function groups.
6. The method according to claim 5 , wherein the number of the function groups is six.
7. The method according to claim 1 , wherein the first status data further includes information on a maximum consumption current required for the second transfer mode.
8. The method according to claim 1 , further comprising:
latching data received through at least one of the data terminals from the outside of the storage device, in accordance with the clock signal having a first frequency, in a normal bus mode; and
latching data received through at least one of the data terminals from the outside of the storage device, in accordance with the clock signal having a second frequency, in a high-speed bus mode, wherein:
the second frequency is higher than the first frequency; and
the first status data further includes information indicating that the storage device supports the high-speed bus mode.
9. The method according to claim 1 , wherein:
the first status data further includes information indicating that the storage device supports an IC card function.
10. The method according to claim 1 , wherein the first status data further includes information on a command system.
11. The method according to claim 1 , further comprising
outputting a response to the first command through the command terminal to the outside of the storage device.
12. The method according to claim 1 , further comprising:
receiving a second command through the command terminal from the outside of the storage device; and
stopping latching data through at least one of the data terminals from the outside of the storage device, in response to the second command.
13. The method according to claim 1 , further comprising
receiving data in a plurality of data blocks, through at least one of the data terminals from the outside of the storage device, wherein
a CRC code is added to each of the data blocks.
14. The method according to claim 13 , further comprising
after receiving each CRC code, outputting a CRC status response indicating a corresponding data block has been received, through one of the data terminals to the outside of the storage device.
15. The method according to claim 13 , further comprising
after receiving each CRC code, outputting a busy signal through one of the data terminals to the outside of the storage device.
16. The method according to claim 1 , further comprising:
latching data received through all data terminals from the outside of the storage device, in a first bit mode; and
latching data received through only one of the data terminals from the outside of the storage device, in a second bit mode.