1. A method for establishing a tuning signal window for use in centering a multi-band voltage controlled oscillator (VCO), the method comprising:
setting the size of the tuning signal window to an initial size;
determining whether the multi-band VCO is churning; and
when the multi-band VCO is churning, expanding the size of the tuning signal window until the multi-band VCO stops churning.
2. The method of claim 1 wherein the initial size of the tuning signal window is zero.
3. The method of claim 1 wherein the size of the tuning signal window is set by a count and wherein expanding the size of the tuning signal window comprises incrementing the count.
4. The method of claim 1 wherein expanding the size of the tuning signal window comprises incrementally expanding the tuning signal window.
5. The method of claim 1 wherein the determining comprises tracking tuning signal window crossings by the VCO.
6. The method of claim 1 wherein the determining comprises tracking frequency band changes.
7. The method of claim 1 further comprising selecting a frequency band that corresponds to a solution and maintaining the selected frequency band.
8. The method of claim 7 further comprising setting the tuning signal window to the initial size in response to a reset event.
9. The method of claim 8 wherein a reset event includes one of a loss of frequency lock and a system restart.
10. The method of claim 1 further comprising offsetting the tuning signal window relative to a zero tuning signal.
11. The method of claim 10 wherein offsetting the tuning signal window comprises determining a window offset as a function of an operating parameter.
12. The method of claim 10 wherein setting the tuning signal window at an offset comprises determining the window offset as a function of an operating temperature related to the VCO.
13. The method of claim 10 wherein expanding the size of the tuning signal window comprises expanding the size of the tuning signal window from the offset.
14. The method of claim 10 wherein expanding the size of the tuning signal window comprises expanding the size of the tuning signal window in equal increments on either side of the offset.
15. The method of claim 10 wherein expanding the size of the tuning signal window comprises individually expanding upper and lower boundaries of the tuning signal window.
16. The method of claim 1 further comprising establishing upper and lower limits for upper and lower boundaries of the tuning signal window and preventing the tuning signal window from being expanded beyond the upper and lower limits.
17. A system for establishing a tuning signal window for use in centering a multi-band voltage controlled oscillator (VCO), the system comprising:
a churn detector configured to determine whether the multi-band VCO is churning and to generate a churning indicator signal when the multi-band VCO is determined to be churning; and
a window size expander configured to expand the size of the tuning signal window in response to the churning indicator signal from the churn detector.
18. The system of claim 17 wherein the window size expander includes a size indicator, the system further comprising reset logic configured to set the size indicator of the window size expander to an initial size.
19. The system of claim 18 wherein the reset logic is configured to set the size indicator of the window size expander to the initial size in response to one of a loss of frequency lock or a system restart.
20. The system of claim 17 wherein the window size expander is configured to incrementally expand the size of the tuning signal window in response to the churning indicator signal from the churn detector.
21. The system of claim 17 wherein the window size expander comprises a digital counter that is incremented by one increment in response to the churning indicator signal.
22. The system of claim 17 wherein the window size expander comprises a counter that is reset to an initial size in response to a reset signal.
23. The system of claim 17 wherein the churn detector is configured to track tuning signal window crossings to determine churning.
24. The system of claim 17 wherein the churn detector is configured to track frequency band changes to determine churning.
25. The system of claim 17 further comprising a window offset controller configured to establish the tuning signal window at an offset relative to a zero tuning signal.
26. The system of claim 25 wherein the window offset controller is configured to determine the window offset as a function of an operating parameter.
27. The system of claim 25 wherein the window offset controller is configured to determine the window offset as a function of an operating temperature related to the VCO.
28. The system of claim 25 wherein the window size expander is configured to expand the size of the tuning signal window from the offset.
29. The system of claim 25 wherein the window size expander is configured to expand the size of the tuning signal window in equal increments on either side of the offset.
30. The system of claim 25 wherein the window size expander comprises an upper boundary counter and a lower boundary counter configured to individually expand upper and lower boundaries of the tuning signal window.
31. The system of claim 25 wherein the window size expander comprises an upper boundary counter that is configured with an upper boundary limit and a lower boundary counter that is configured with a lower boundary limit.
32. A system for centering a multi-band voltage controlled oscillator (VCO), the system comprising:
a band select counter configured to generate a band select signal for selecting a frequency band of the multi-band VCO;
a window comparator in signal communication with said band select counter configured to compare a tuning signal to a tuning signal window and to output a comparison signal that allows the band select signal to be changed only when the tuning signal is outside the tuning signal window; and
window size control logic comprising;
a churn detector configured to determine whether the multi-band VCO is churning and to generate a churning indicator signal when the multi-band VCO is determined to be churning; and
a window size expander configured to expand the size of the tuning signal window in response to the churning indicator signal from the churn detector.
33. The system of claim 32 wherein the window size expander includes a size indicator, the window size control logic further comprising reset logic configured to set the size indicator of the window size expander to an initial size.
34. The system of claim 33 further including a controller configured to allow the band select signal to change N times after lock is achieved.
35. The system of claim 32 further comprising a window offset controller configured to establish the tuning signal window at an offset relative to a zero tuning signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system comprising:
a first module of a first chain of modules, each adjacent pair of said first chain of modules communicatively coupled in series to a programmable logic controller (PLC), said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said first chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.
2. The system of claim 1, further comprising:
a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series to said PLC.
3. The system of claim 1, further comprising:
a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series to said PLC, wherein said second chain of modules comprise communication modules.
4. The system of claim 1, further comprising:
said PLC.
5. The system of claim 1, wherein said first switch is adapted to close subsequent to said assignment of said module address to said first module.
6. The system of claim 1, wherein said second switch is dynamically controlled to allow transmission from the first module toward the PLC when the first module has information to send, or selects the second repeater to allow any message presented from the direction of the second module to be repeated toward the PLC.
7. The system of claim 1, wherein first chain of modules comprises only InputOutput modules.
8. The system of claim 1, wherein said first module is implemented via an ASIC controlled by machine instructions.
9. The system of claim 1, wherein said PLC is implemented via an ASIC controlled by machine instructions.
10. The system of claim 1, wherein said first module is implemented via software.
11. The system of claim 1, wherein said first module is implemented via firmware.
12. The system of claim 1, wherein said PLC is implemented via firmware.
13. The system of claim 1, wherein said first module is implemented via an FPGA controlled by machine instructions.
14. The system of claim 1, wherein said PLC is implemented via an FPGA controlled by machine instructions.
15. A method comprising:
transmitting a message from a programmable logic controller (PLC) that is communicatively coupled to a first module of a first chain of modules, each adjacent pair of said first chain of modules communicatively coupled in series, each of said first chain of modules InputOutput modules adapted to communicate with said PLC in hard real-time, said PLC communicatively coupled to a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series, each of said second chain of modules a communications module, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said first chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module, each of said 8B10B encoded frames comprising message type field of a size that corresponds to eight bits, a value stored in said message type field indicative of content of a data field of said frame, said message type field following a first ordered sequence of fields comprised by said frame, said first ordered sequence of fields, a preamble field, a start-of-frame field, a destination address field of a size that corresponds to eight bits, a length field, and a source address field of a size that corresponds to eight bits, said message type field followed by a second ordered sequence of fields comprised by said frame, said second ordered sequence comprising a data field, a cyclic redundancy check field of a size that corresponds to 32 bits, and an end of frame field.
16. A machine-readable medium comprising machine instructions for activities comprising:
communicatively coupling a programmable logic controller (PLC) to a first module of a chain of modules, each adjacent pair of said chain of modules communicatively coupled in series, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.
17. A system comprising:
a circuit adapted to communicatively couple a programmable logic controller (PLC) to a first module of a chain of modules, each adjacent pair of said chain of modules communicatively coupled in series, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.