BC41B143A-ANN-E4 ETC, BC41B143A-ANN-E4 Datasheet - Page 79

• Manufacturer Part Number: BC41B143A-ANN-E4
• Description: Bluecore 4-rom CSP EDR Single Chip Bluetooth v2.0 + EDR System
• Manufacturer: ETC

11.11 Resetting BlueCore4-ROM CSP
BlueCore4-ROM CSP can be reset from several sources:
The RESETB pin is an active low reset and is internally filtered to prevent short glitches from causing a reset. A
reset is performed between 1.5 and 4.0ms following RESETB being active. CSR recommends that RESETB is
applied for a period greater than 5ms.
The power on reset occurs when the VDD_CORE supply falls below typically 1.5V and is released when
VDD_CORE rises above typically 1.6V.
At reset the digital I/O pins are set to inputs for bi-directional pins and outputs are tri-stated. The PIOs have weak
pull-downs.
Following a reset, BlueCore4-ROM CSP assumes that XTAL_IN is 40MHz, which ensures that the internal clocks
run at a safe (low) frequency until BlueCore4-ROM CSP is configured for the actual XTAL_IN frequency. If there
is no clock present at XTAL_IN, the oscillator in BlueCore4-ROM CSP free runs, again at a safe frequency
though RF operation will not be possible until a clock is provided at XTAL_IN.
11.11.1 Pin States during Reset
Table 11.13 shows the pin states of BlueCore4-ROM CSP during reset.
Pin name
PIO[10:0]
PCM_OUT
PCM_IN
PCM_SYNC
PCM_CLK
UART_TX
UART_RX
UART_RTS
UART_CTS
USB_DP
USB_DN
SPI_CSB
SPI_CLK
SPI_MOSI
SPI_MISO
AIO[2], AIO[0]
RESETB
TX_A
TX_B
XTAL_IN
XTAL_OUT
BC41B143A-ds-002Pd
!
!
!
!
the RESETB pin
power on reset
a UART break condition
via a software configured watchdog timer
Table 11.13: Pin States of BlueCore4-ROM CSP on Reset
This material is subject to CSR’s non-disclosure agreement
State: BlueCore4-ROM CSP
Input with weak pull-down
Tri-stated with weak pull-down
Input with weak pull-down
Input with weak pull-down
Input with weak pull-down
Tri-stated with weak pull-up
Input with weak pull-down
Tri-stated with weak pull-up
Input with weak pull-down
Input with weak pull-down
Input with weak pull-down
Input with weak pull-up
Input with weak pull-down
Input with weak pull-down
Tri-stated with weak pull-down
Connected to VSS
Input with weak pull-up
High impedance
High impedance
High impedance, 250kΩ to XTAL_OUT
High impedance, 250kΩ to XTAL_IN
© Cambridge Silicon Radio Limited 2005
Production Information
Device Terminal Descriptions
Page 79 of 89