BC41B143A-ds-001Pe CSR, BC41B143A-ds-001Pe Datasheet - Page 71

• Manufacturer Part Number: BC41B143A-ds-001Pe
• Description: Blue Core ROM
• Manufacturer: CSR

10.6.2 Writing to BlueCore4-ROM
To write to BlueCore4-ROM, 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.
10.6.3 Reading from BlueCore4-ROM
Reading from BlueCore4-ROM 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]). BlueCore4-ROM 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.
10.6.4 Multi Slave Operation
BlueCore4-ROM should not be connected in a multi slave arrangement by simple parallel connection of slave
MISO lines. When BlueCore4-ROM is deselected (SPI_CSB = 1), the SPI_MISO line does not float, instead,
BlueCore4-ROM outputs 0 if the processor is running or 1 if it is stopped.
BC41B143A-ds-001Pe
SPI_MOSI
SPI_MISO
SPI_MOSI
SPI_MISO
SPI_CSB
SPI_CSB
SPI_CLK
SPI_CLK
Processor
State
Processor
State
Reset
Reset
C7
C7
Read_Command
C6
Write_Command
C6
MISO Not Defined During Address
C1
C1
C0 A15 A14
C0
A15
This material is subject to CSR’s non-disclosure agreement
Address(A)
A14
Address(A)
A1
Figure 10.17: Write Operation
Figure 10.18: Read Operation
A0
© Cambridge Silicon Radio Limited 2005
A1
T15 T14
A0
Check_Word
Production Information
MISO Not Defined During Write
D15 D14
T1
Data(A)
T0
D15 D14
D1
Data(A)
D0
D15
D1
D14
D0 D15 D14
Data(A+1)
Don't Care
D1
Data(A+1)
D0
D1
D15
D0
Device Terminal Descriptions
D14
D15 D14
etc
D1
etc
D1
D0
D0
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End of Cycle
End of Cycle
Don't Care
Processor
Processor
State
State