BC352239A Datasheet, PDF (71/116 Pages) List of Unclassifed Manufacturers – BlueCore 3-Multimedia External

Device Terminal Descriptions
8.7.2 Writing to BlueCore3-Multimedia External
To write to BlueCore3-Multimedia External, the 8-bit write command (00000010) is sent first (C[7:0]) followed by
a 16-bit address (A[15:0]). The next 16-bits (D[15:0]) clocked in on SPI_MOSI are written to the location set by
the address (A). Thereafter for each subsequent 16-bits clocked in, the address (A) is incremented and the data
written to consecutive locations until the transaction terminates when SPI_CSB is taken high.
SPI_CSB
Reset
Write_Command
Address(A)
Data(A)
Data(A+1)
End of Cycle
etc
SPI_CLK
SPI_MOSI
C7 C6
C1 C0 A15 A14
A1 A0 D15 D14
D1 D0 D15 D14
D1 D0 D15 D14
D1 D0
Don't Care
SPI_MISO
Processor
State
MISO Not Defined During Write
Figure 8.26: Write Operation
Processor
State
8.7.3 Reading from BlueCore 3-Multimedia External
Reading from BlueCore3-Multimedia External is similar to writing to it. An 8-bit read command (00000011) is sent
first (C[7:0]), followed by the address of the location to be read (A[15:0]). BlueCore3-Multimedia External then
outputs on SPI_MISO a check word during T[15:0] followed by the 16-bit contents of the addressed location
during bits D[15:0].
The check word is composed of {command, address [15:8]}. The check word may be used to confirm a read
operation to a memory location. This overcomes the problems encountered with typical serial peripheral interface
slaves, whereby it is impossible to determine whether the data returned by a read operation is valid data or the
result of the slave device not responding.
If SPI_CSB is kept low, data from consecutive locations is read out on SPI_MISO for each subsequent 16 clocks,
until the transaction terminates when SPI_CSB is taken high.
SPI_CSB
Reset
Read_Command
Address(A)
Check_Word
Data(A)
Data(A+1)
End of Cycle
etc
SPI_CLK
SPI_MOSI
C7 C6
C1 C0 A15 A14
A1 A0
Don't Care
SPI_MISO
Processor
State
MISO Not Defined During Address
T15 T14
T1 T0 D15 D14
D1 D0 D15 D14
Figure 8.27: Read Operation
D1 D0 D15 D14
D1 D0
Processor
State
8.7.4 Multi Slave Operation
BlueCore3-Multimedia External should not be connected in a multi slave arrangement by simple parallel
connection of slave MISO lines. When BlueCore3-Multimedia External is deselected (SPI_CSB = 1), the
SPI_MISO line does not float, instead, BlueCore3-Multimedia External outputs 0 if the processor is running or 1 if
it is stopped.
BC352239A-ds-001Pc
© Cambridge Silicon Radio Limited 2004
Production Information
Page 71 of 116