BL652 Development Kit
User Guide
Embedded Wireless Solutions Support Center:
http://ews-support.lairdtech.com
www.lairdtech.com/bluetooth
33
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By default, these are GPIO pins. Only when FlashOpen() command appears in the smartBASIC application script
are these lines dedicated to SPI and for talking to the off-board flash.
Figure 17: Optional external serial SPI flash IC (U18) schematic and PCB
The smartBASIC application for this external optional serial SPI flash IC will be available in the future in the
GitHub smartBASIC sample application repository on the BL652 product page at
https://github.com/LairdCP/BL652-Applications
8.3.7
Optional 32.76 kHz Crystal
The BL652 on-chip 32.768kHz RC oscillator provides the standard accuracy of ±250 ppm, with calibration
required every 8 seconds (default) to stay within ±250 ppm.
The BL652 also allows, as an option, to connect an external higher accuracy (±20 ppm) 32.768 kHz crystal to the
BL652-SX-xx pins SIO_01/XL2 (pin 24) and SIO_00/XL1 (pin 25). This provides improved protocol timing and helps
with radio power consumption in the system standby doze/deep sleep modes by reducing the time that the Rx
window must be open.
To connect the optional external 32.76kHz crystal oscillator circuit to the BL652 module, remove R127 and R128
and short SB8 and short SB9.
SB5 NOPOP (Solderbridge_Open)
1
1
2
2
GND
Flash_SPI_CLK_SIO_16
SB4 NOPOP (Solderbridge_Open)
1
1
2
2
VCC_IO_UART
SIO_20
SIO_16
GND
Flash_SPI_MOSI_SIO_20
R126
10K
R125
10K
VCC_IO_UART
Flash_SPI_CS#_SIO_12
U18
4Mx1,SPI,1.65~3.6V
CS#
1
SO/SIO1
2
WP#
3
GND
4
SI/SIO0
5
CLK
6
HOLD#
7
VCC
8
GN
D
9
VCC_IO_UART
Flash_SPI_MISO_SIO_14
SB6
NOPOP (Solderbridge_Open)
1
1
2
2
SB7
NOPOP (Solderbridge_Open)
1
1
2
2
SIO_12
SIO_14
C5
0.1uF,16V
GND
GND
R127
0R
R128
0R
SIO_0_Header
GND
Y 3
32.768KHz,20ppm,9pF
1
2
SIO_0
XL1
SIO_1
C70
10pF,50V
C71
12pF, 50V
XL2
SIO_1_Header
SB8 NOPOP (Solderbridge_Open)
1
1
2
2
SB9 NOPOP (Solderbridge_Open)
1
1
2
2
NOPOP (PIN HEADER,2.54mm 1X2P)
J44
1
1
2
2
SIO_0_Header
SIO_1_Header