Configurable timers

[tgtakaoka]

Small MSP430 chips have the following varieties of timer configurations. TinyOS for small MSP430 should have configurable and wire-able timer modules.

• Timer A2
• Timer A3
• Timer A3, A3
• Timer A3, B3
• Timer A3, B7
• Timer A3, A3, B7
• Timer A5, A3, A3, B7
• Timer A3, A3, A2, A2, B7
• Timer A3, A3, B3, B3, B3
• Timer A3, D3, D3

And chips also have a varieties of clock modules and oscillators. Those should also be configurable and wire-able.

• BCS module
• BCS+ module
• FLL+ module
• UCS module
• CS module
• VLO oscillator
• DCO oscillator
• LFXT1 oscillator
• XT2/HFXT2 oscillator

It would be great if there can be clock calibration modules, for instance VLO calibrated by DCO, and DCO calibrated by LFXT1, and etc.

[tgtakaoka]

The config-timers branch has been created for this issue. https://github.com/tgtakaoka/tinyos-msp430/tree/config-timers

[tgtakaoka]

pr#24 and pr#25 solved this issue in some extent.

For timer configuration,

• on MCU that has one Timer A and no Timer B, Timer A is used for millisecond timer and no microsecond timer configured.
• on MCU that has more than two Timer A and no Timer B, the Timer A0 is used for millisecond timer and Timer A1 is used for microsecond timer.

• on MCU that has Timer A and Timer B, Timer A is used for millisecond timer and Timer B is used for microsecond timer. Note that this usage is opposite of upstream/tinyos-prod.

  There is no Timer D support yet.

For clock system support,

• on MCU that has basic clock module, DCO is calibrated to 4MiHz using 32kiHz LFXT1.

• on MCU that has basic clock module+, DCO is calibrated to 8MiHz using 32kiHz LFXT1.

  This can be overridden by providing custom Msp430CalibrateDco configuration/module that set DCO using CALDCO/CALBC1 calibrated values.

  Note that the DCO frequency is compatible with upstream/tinyos-prod, so that serial module constants should be the same.

• VLO support is immature but should work. VLO is used as timebase for millisecond timer but not calibrated. We may want to calibrate VLO based on DCO frequency.

• CS, UCS, and FLL+ aren't supported yet. We may not want to support XT1/Xt2.

  And config-timers branch is abandoned.