Termination control device, and universal serial bus system
View Patent ↗It is intended to provide a terminal control device and a universal serial bus system capable of achieving stable system operation wherein the termination control device controls termination considering propagation delay time required for bus voltage level to shift to termination voltage when a universal serial bus system is terminated and an erroneous detection due to propagation delay time of voltage level shifting is avoided, accordingly. A pull-up start signal PU is inputted to a mask counter 11 , timing operation is conducted in a manner of count operation. As a result of count operation, mask count signals MC are outputted to a comparator 13 . Masking-time setting signals SC are inputted to the comparator 13 . The mask count signals MC and the masking-time setting signals SC are compared to calculate a predetermined length of masking time that begins with start of pull-up. During this masking time, detection of SE 0 state or bus-reset state is masked. Thereby, there can be avoided erroneous detection of an SE 0 during transition period after start-up of the system, and termination control can surely be conducted.
1. A termination control device capable of switching presence/absence of termination for predetermined signal line(s) for a universal serial bus, the termination control device comprising:
a permission timing setting section for outputting a permission signal by timing predetermined length of time from a termination start signal; and
a state detecting section for detecting a state of the predetermined signal line(s), the state detecting section being activated based on the permission signal.
2. A termination control device according to claim 1 further comprising:
a timing section for starting to time based on the termination start signal; and
a comparator for outputting the permission signal based on a result of comparison between timing time by the timing section and the predetermined time.
3. A termination control device according to claim 1 , wherein the predetermined time can be set outside of the termination control device.
4. A termination control device according to claim 1 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section includes a duration monitoring section for monitoring duration of an SE 0 state at the predetermined signal line(s), the duration monitoring section being activated based on the permission signal.
5. A termination control device according to claim 4 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section includes a bus-reset detecting section for detecting a bus-reset state based on a duration signal from the duration monitoring section, the duration monitoring section being activated based on the permission signal.
6. A termination control device according to claim 1 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section can detect an SE 0 state at the predetermined signal line(s) upon activation based on the permission signal.
7. A termination control device according to claim 1 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section can detect a bus-reset state being propagated through the predetermined signal line(s) upon activation based on the permission signal.
8. A termination control device capable of switching presence/absence of termination for predetermined signal line(s) for a universal serial bus, the termination control device comprising:
a voltage detecting section for detecting voltage level of the predetermined signal lines; and
a state detecting section for detecting a state of the predetermined signal line(s), the state detecting section being activated based on an alarm signal outputted from the voltage detecting section when voltage level at the predetermined signal line(s) reaches termination voltage level.
9. A termination control device according to claim 8 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section includes a duration monitoring section for monitoring duration of an SE 0 state at the predetermined signal line(s), the duration monitoring section being activated based on the alarm signal.
10. A termination control device according to claim 9 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section includes a bus-reset detecting section for detecting a bus-reset state based on a duration signal from the duration monitoring section, the duration monitoring section being activated based on the alarm signal.
11. A termination control device according to claim 8 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section can detect an SE 0 state at the predetermined signal line(s) upon activation based on the alarm signal.
12. A termination control device according to claim 8 , wherein the termination corresponds to pulling up of voltage level at the predetermined signal line(s), and the state detecting section can detect a bus-reset state being propagated through the predetermined signal line(s) upon activation based on the alarm signal.
13. A termination control device capable of switching presence/absence of termination for predetermined signal line(s) for a universal serial bus, the termination control device comprising:
a permission timing setting section for outputting a permission signal by timing predetermined length of time from a termination start signal;
a voltage detecting section for detecting voltage level of the predetermined signal line(s); and
a state detecting section for detecting a state of the predetermined signal line(s) upon activation based on mechanism that the permission signal and an alarm signal outputted from the voltage detecting section when voltage level of the predetermined signal line(s) reaches termination voltage level are inputted and activated.
14. Universal serial bus system capable of switching presence/absence of termination for predetermined signal line(s), the universal serial bus system comprising:
a permission timing setting section for outputting a permission signal by timing predetermined length of time from a termination start signal; and
a state detecting section for detecting a state of the predetermined signal line(s), the state detecting section being activated based on the permission signal.
15. Universal serial bus system capable of switching presence/absence of termination for predetermined signal line(s), the universal serial bus system comprising:
a voltage detecting section for detecting voltage level of the predetermined signal line(s); and
a state detecting section for detecting state of the predetermined signal line(s), the state detecting section being activated based on an alarm signal outputted from the voltage detecting section when voltage level at the predetermined signal line(s) reaches termination voltage level.
16. Universal serial bus system capable of switching presence/absence of termination for predetermined signal line(s), the universal serial bus system comprising:
a permission timing setting section for outputting a permission signal by timing predetermined length of time from a termination start signal;
a voltage detecting section for detecting voltage level of the predetermined signal line(s); and
a state detecting section for detecting a state of the predetermined signal line(s), the state detecting section being activated based on mechanism that the permission signal and an alarm signal outputted from the voltage detecting section when voltage level of the predetermined signal line(s) reaches termination voltage level are inputted and activated.