SD switch box in a cellular handset
View Patent ↗An SD switch box embedded within a cellular handset, including circuitry for switching access to NAND storage that is embedded within the cellular handset, between a consumer electronic device that is external to and connected to the cellular handset, and between a base band modem that is embedded within the cellular handset, so as to enable shared use of the NAND memory by the consumer electronic device and by the base band modem, thereby enabling the cellular handset to be operational for cellular communication via its internal base band modem while its internal NAND memory is accessible to the external consumer electronics device.
1. A secure digital (SD) switch box embedded within a cellular handset, comprising:
circuitry for switching access to NAND memory that is embedded within the cellular handset, between a consumer electronic device that is external to and connected to the cellular handset and that operates as a host device for the cellular handset, and between a base band modem that is embedded within the cellular handset, so as to enable shared use of the NAND memory by the consumer electronic device and by the base band modem;
two separate SD ports, comprising:
a first SD port for communication between the SD switch box and the base band modem; and
a second SD port for communication between the SD switch box and the consumer electronic device,
wherein said circuitry receives an access grant message from the consumer electronic device via said second SD port and, in response thereto, sets a busy state on said second SD port in order to enable the base band modem to access the NAND memory, and
wherein said circuitry receives a free message via said first SD port from the base band modem when the base band modem has completed its access to the NAND memory, and, in response thereto, releases the busy state from said second SD port.
2. The SD switch box of claim 1 , further comprising a third SD port for communication between the SD switch box and a NAND controller for the NAND memory, the NAND controller also being embedded within the cellular handset.
3. The SD switch box of claim 1 further comprising a UART port for communication between the SD switch box and the base band modem.
4. The SD switch box of claim 3 wherein said circuitry reads a secondary boot code image from the NAND memory, and loads the secondary boot code image to the base band modem via said UART port.
5. The SD switch box of claim 1 further comprising:
a first mailbox into which the base modem writes the free message; and
a second mailbox into which the consumer electronic device writes the access grant message.
6. The SD switch box of claim 5 wherein said circuitry initiates an interrupt to the consumer electronic device when the base band modem completes a write operation to said first mailbox.
7. The SD switch box of claim 1 , further comprising a NAND controller for the NAND memory.
8. The SD switch box of claim 7 further comprising a UART port for communication between the SD switch box and the base band modem.
9. The SD switch box of claim 8 wherein said circuitry reads a secondary boot code image from the NAND memory, and loads the secondary boot code image to the base band modem via said UART port.
10. The SD switch box of claim 7 further comprising:
a first mailbox into which the base band modem writes the free message; and
a second mailbox into which the consumer electronic device writes the grant access message.
11. The SD switch box of claim 10 wherein said circuitry initiates an interrupt to the consumer electronic device when the base band modem completes a write operation to said first mailbox.