BC41B143A-ds-001Pe CSR, BC41B143A-ds-001Pe Datasheet - Page 70

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

10.5.9 USB 1.1 Compliance
BlueCore4-ROM is qualified to the USB specification v1.1, details of which are available from
The specification contains valuable information on aspects such as PCB track impedance, supply inrush current
and product labelling.
Although BlueCore4-ROM meets the USB specification, CSR cannot guarantee that an application circuit
designed around the chip is USB compliant. The choice of application circuit, component choice and PCB layout
all affect USB signal quality and electrical characteristics. The information in this document is intended as a guide
and should be read in association with the USB specification, with particular attention being given to Chapter 7.
Independent USB qualification must be sought before an application is deemed USB compliant and can bear the
USB logo. Such qualification can be obtained from a USB plugfest or from an independent USB test house.
Terminals USB_DP and USB_DN adhere to the USB specification 2.0 (Chapter 7) electrical requirements.
10.5.10 USB 2.0 Compatibility
BlueCore4-ROM is compatible with USB v2.0 host controllers; under these circumstances the two ends agree the
mutually acceptable rate of 12Mbits/s according to the USB v2.0 specification.
10.6
BlueCore4-ROM uses 16-bit data and 16-bit address serial peripheral interface, where transactions may occur
when the internal processor is running or is stopped. This section details the considerations required when
interfacing to BlueCore4-ROM via the four dedicated serial peripheral interface terminals. Data may be written or
read one word at a time or the auto increment feature may be used to access blocks.
10.6.1 Instruction Cycle
The BlueCore4-ROM is the slave and receives commands on SPI_MOSI and outputs data on SPI_MISO. The
instruction cycle for a SPI transaction is shown in Table 10.8.
With the exception of reset, SPI_CSB must be held low during the transaction. Data on SPI_MOSI is clocked into
the BlueCore4-ROM on the rising edge of the clock line SPI_CLK. When reading, BlueCore4-ROM will reply to
the master on SPI_MISO with the data changing on the falling edge of the SPI_CLK. The master provides the
clock on SPI_CLK. The transaction is terminated by taking SPI_CSB high.
Sending a command word and the address of a register for every time it is to be read or written is a significant
overhead, especially when large amounts of data are to be transferred. To overcome this BlueCore4-ROM offers
increased data transfer efficiency via an auto increment operation. To invoke auto increment, SPI_CSB is kept
low, which auto increments the address, while providing an extra 16 clock cycles for each extra word to be written
or read.
BC41B143A-ds-001Pe
Serial Peripheral Interface
1
2
3
4
5
Reset the SPI interface
Write the command word
Write the address
Write or read data words
Termination
Table 10.8: Instruction Cycle for an SPI Transaction
This material is subject to CSR’s non-disclosure agreement
© Cambridge Silicon Radio Limited 2005
Production Information
Hold SPI_CSB high for two
SPI_CLK cycles
Take SPI_CSB low and clock in the
8-bit command
Clock in the 16-bit address word
Clock in or out 16-bit data word(s)
Take SPI_CSB high
Device Terminal Descriptions
http://www.usb.org
Page 70 of 102