User manual

Installation and Operation
© 2012 Microchip Technology Inc. DS52056A-page 15
When GP8 is configured for its dedicated functionality, the pin can be used as a bus
release request for MCP2210 coming from another master. GP7 (configured for its
dedicated functionality) is used as an SPI bus release acknowledge signal towards the
requesting master. When an external SPI master requests the MCP2210 to release the
bus, the device completes the current SPI transfer (or it can be cancelled by the PC
application sending the proper USB command), then releases the bus and signals the
event on the acknowledge pin (GP7). The second master now has ownership of the
bus, and can keep it, as long as the SPI bus request pin (GP8) is kept asserted.
By using the dedicated functionality of the GP7 and GP8, the MCP2210 can be used
in a multiple SPI master system.
FIGURE 2-3: MCP2210 TYPICAL USAGE DIAGRAM
MCP2210
SPI bus
Chip-Select lines
MOSI, MISO, SCK
USB
USB-to-SPI
bridge
SPI slave chip #1 SPI slave chip #n
External
Interrupt
(GP6)
Interrupt
Interrupt
...
SPI Master #2
SPI Bus Release Request
SPI Bus Release
Acknowledge
External
Interrupt
GP8
GP7