16-6
MC9328MX1 Reference Manual
MOTOROLA
Bluetooth Accelerator (BTA)
When the unit is the master of a piconet, its NativeClk is used for timing of slots, hopping frequency
sequence, whitening/de-whitening initialization, and so on.
NativeClk
is a free-running 28 bit counter updated at a frequency of 3.2 kHz. The 3.2 kHz clock is
generated by dividing the high precision 8 MHz clock by 2,500 using a 12-bit counter (NativeCount).
Bluetooth specifications stipulate that, in connection states of high activity, a worst case accuracy of ± 20
ppm is expected for the native clock. In low-power states (Standby, Hold or Park modes), a relaxed
accuracy of ± 250 ppm is allowed.
NOTE:
When temperature drift and aging are taken into account, the requirement
of the high precision clock is more likely to be around ± 10 ppm.
EstimatedClk
is a clock that is maintained by the unit when it operates as a slave, and it keeps track of a
remote master’s NativeClk. During a page scan, when the slave unit receives an access code trigger from
the master, it presets the EstimatedCount with an expected count and sets the two least significant bits of
EstimatedClk to “00.” This value causes the unit to respond 625 µs later, relative to the beginning of the
time slot, regardless of whether it receives the first or second page within the time slot.
Later in the link setup, the EstimatedClk is updated with the remote master’s native clock, which is sent in
the FHS packet. EstimatedClk is incremented by the EstimatedCount. During active connection state,
whenever the access code is triggered from the master’s transmission, EstimatedCount is updated with an
expected count, therefore preventing the EstimatedClk from drifting away from the remote master’s
NativeClk.
A third value, OffsetClk, maintains the difference between EstimatedClk and NativeClk. OffsetClk is
updated at every NativeClk tick. Writing to the OFFSET_CLK_LOW and OFFSET_CLK_HIGH registers
will update EstimatedClk with the sum of NativeClk and OffsetClk on the next NativeClk tick.
16.3.1.2.2 Interrupt Generation
The Bluetooth core provides three interrupt lines:
1. A combination of three interrupts that are Logical-OR’ed together into a single active-high
wire. This one-shot interrupt is termed “BTsys.”
2. An interrupt triggered by the Bluetooth application timer termed “BTtim.”
3. An interrupt generated during the wake-up sequence termed “BTwui.”
The interrupts are summarized and described in Table 16-3 on page 16-7.
EstimatedClk
28
3.2 kHz
Low (power down)
High (operation)
Estimate of the remote master’s
NativeClk. Set by software and updated
by the EstimatedCount.
OffsetClk
28
3.2 kHz
Low (power down)
High (operation)
Difference between NativeClk and
EstimatedClk. This is updated each
SysTick.
Table 16-2. Bluetooth Clocks and Counters (Continued)
Name
Bit Size
Input Frequency
Precision
Purpose
Summary of Contents for DragonBall MC9328MX1
Page 68: ...1 12 MC9328MX1 Reference Manual MOTOROLA Introduction ...
Page 86: ...2 18 MC9328MX1 Reference Manual MOTOROLA Signal Descriptions and Pin Assignments ...
Page 116: ...3 30 MC9328MX1 Reference Manual MOTOROLA Memory Map ...
Page 126: ...4 10 MC9328MX1 Reference Manual MOTOROLA ARM920T Processor ...
Page 160: ...8 8 MC9328MX1 Reference Manual MOTOROLA System Control ...
Page 272: ...13 32 MC9328MX1 Reference Manual MOTOROLA DMA Controller ...
Page 281: ...Programming Model MOTOROLA Watchdog Timer Module 14 9 ...
Page 282: ...14 10 MC9328MX1 Reference Manual MOTOROLA Watchdog Timer Module ...
Page 300: ...15 18 MC9328MX1 Reference Manual MOTOROLA Analog Signal Processor ASP ...
Page 438: ...18 16 MC9328MX1 Reference Manual MOTOROLA Serial Peripheral Interface Modules SPI 1 and SPI 2 ...
Page 478: ...19 40 MC9328MX1 Reference Manual MOTOROLA LCD Controller ...
Page 574: ...21 32 MC9328MX1 Reference Manual MOTOROLA Memory Stick Host Controller MSHC Module ...
Page 598: ...23 16 MC9328MX1 Reference Manual MOTOROLA Real Time Clock RTC ...
Page 670: ...24 72 MC9328MX1 Reference Manual MOTOROLA SDRAM Memory Controller ...
Page 726: ...25 56 MC9328MX1 Reference Manual MOTOROLA SmartCard Interface Module SIM ...
Page 736: ...26 10 MC9328MX1 Reference Manual MOTOROLA General Purpose Timers ...
Page 854: ...29 18 MC9328MX1 Reference Manual MOTOROLA I2C Module ...
Page 900: ...30 46 MC9328MX1 Reference Manual MOTOROLA Synchronous Serial Interface SSI ...
Page 942: ...32 26 MC9328MX1 Reference Manual MOTOROLA GPIO Module and I O Multiplexer IOMUX ...