User's Manual

Datalogic Scanning, Inc
959 Terry Street
Eugene, Oregon 97402
Page 73 10/23/2009
Revision X2
reference is required (for instance, when the BlueCore is in deep sleep).
If set to 0, no PIO is used as a clock request. If set to 1, PIO[6] is active when an external clock reference is
required, and is inactive otherwise. If set to 2, PIO[2] is active when an external clock reference is required,
and is inactive otherwise. If set to 3, PIO[2] is active when an external clock reference is required or if
PIO[3] is high, and is inactive when a clock reference is not required and PIO[3] is low.
Values of 2 and 3 are only useful for versions of the BlueCore hardware starting with BlueCore2-ROM.
In the default configuration, a PIO is held high when active and held low when inactive. In versions of
BlueCore from BlueCore3-ROM, this behaviour can be altered by setting
PSKEY_CLOCK_REQUEST_FEATURES
.
Key Name Key Number Type Default Setting
PSKEY_RX_MIN_ATTEN 0x0249 uint16 0
Minimum allowed attenuation for receiver apart from channels 29,30,31,61,62,63. This can be used to
improve C/I performance and to improve consistency of receiver sensitivity over frequency range.
Key Name Key Number Type Default Setting
PSKEY_XTAL_TARGET_AMPLITUDE 0x024b uint8 204
This sets the target crystal oscillation amplitude as determined by the device's internal circuitry. This is not
as will be measured using external instruments.
Pre-BC5 the pskey is used to set an absolute internal oscillation amplitude. For BC5 the pskey sets a % of
the maximum measured internal amplitude, it is a relative internal level.
Note: As a rule, the default value issued by CSR will not need to be changed.
The crystal bias level is chosen such that the oscillation amplitude is as close as possible to the target. This
is done by gradually decreasing the crystal bias level from its maximum until the target amplitude is
reached.
The target amplitude is treated as a minimum; as long as it is achievable, the firmware will use a crystal
bias that produces at least the requested amplitude.
It was originally possible to set the crystal bias level directly but that control has been superseded by this
improved "set and measure" approach. This provides correct operation with some variance in crystal
parameters and also tracks over changes in temperature, it is not intended as a level control mechanism per-
se.
A module designer may wish to test the effect of changing the configured target amplitude across a
representative sample of modules and adjust the production target amplitude accordingly.
This assessment of level should be made by observing the correct operation of the unit rather than trying to
measure the amplitude directly.
Typically, setting a value larger than the correct one will lead to a stable crystal that draws an unnecessarily
large current. Setting a value smaller than the correct one can lead to the system clock being unstable and it
may even stop.