UM-B-077
DA14681 Wearable Development Kit Hardware Manual
User Manual
Revision 1.2
06-Apr-2017
CFR0012
13 of 47
© 2017 Dialog Semiconductor
4.1.2
QSPI Data Flash Memory
The DA14681 wearable reference design includes an external QSPI Data Flash memory from
Winbond. The W25Q80EW is a 1.8 V, 8 Mbit Flash memory that supports the standard Serial
Peripheral Interface (SPI), Dual/Quad I/O SPI as well as 2-clock instruction cycle Quad Peripheral
Interface (QPI), Serial Clock, Chip Select, Serial Data I/O0 (DI), I/O1(D0), I/O2 (/WP) and
I/O3(/HOLD).
QSPI is supplied from the V18 voltage rail. The same supply voltage is connected to the DA14681
VDDIO pin.
Figure 8: QSPI Data Flash Schematic
The DA14681 uses the external Flash memory for directly executing code with some help from the
internal cache, or simply for mirroring the contents in RAM during booting (option selectable via the
binary image header).
4.1.3
Crystal Oscillators
The DA14681 SoC has two Digitally Controlled Crystal Oscillators (DCXO), one at 16 MHz
(XTAL16M) and a second at 32.768 kHz (XTAL32K). The 32.768 kHz oscillator has no trimming
capabilities and is used as the clock for the Extended/Deep Sleep modes. The 16 MHz oscillator can
be trimmed.
The crystals used on the wearable reference design are specified in
Table 2
and
Table 3
.
Table 2: Y1 (16 MHz Crystal) Characteristics
Reference Designator
Value
Part Number
7M-16.000MEEQ-T
Frequency
16 MHz
Accuracy
±10 ppm
Load Capacitance (CL)
10 pF
Shunt Capacitance (C0)
3 pF
