User manual

MCP2210 Evaluation Kit User’s Guide

FIGURE 2-7: MCP2210 TYPICAL USAGE DIAGRAM

When a system requires more than one SPI master sharing the same bus, an

arbitration scheme needs to be developed, to prevent multiple SPI masters trying to

access the bus at the same time. MCP2210 has support for such a mechanism, using

GP7 and GP8 (configured for dedicated pin functionality) for this purpose.

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 ded-

icated functionality) is used as an SPI bus release acknowledge signal towards the

requesting master. When an external SPI master requests that the MCP2210 release

the bus, the MCP2210 completes the current SPI transfer (or it can be cancelled by the

PC application by sending the proper USB command). Then it releases the bus, and

signals this event on the acknowledge pin (GP7). The second master now has owner-

ship of the bus and can keep it as long as the SPI bus request pin (GP8) is kept

asserted.

In conclusion, when the dedicated functionality of the GP7 and GP8 are used,

MCP2210 can be used in a multiple SPI master system.

MCP2210

SPI bus

Chip-Select lines

MOSI, MISO, SCK

CS0-CS8

USB

USB-to-SPI

bridge

SPI slave chip #1 SPI slave chip #n

External

Interrupt

(GP6)

Interrupt

...