Support structures for an intelligent low power serial bus
First Claim
Patent Images
1. In a peripheral device, a serial bus support circuit comprising:
- a power supply line;
a downstream interrupt line coupled to said power supply line wherein upon connection of a downstream peripheral device to said downstream interrupt line, said downstream interrupt line has a first level, and upon disconnection of said downstream peripheral device from said downstream interrupt line, said downstream interrupt line has a second level;
an upstream interrupt line; and
a bus interface circuit having a downstream interrupt in terminal coupled to said downstream interrupt line, and an upstream interrupt out terminal coupled to said upstream interrupt line wherein said bus interface circuit passes a signal on said downstream interrupt in terminal to said upstream interrupt out terminal so that upon said downstream peripheral device being disconnected from said downstream interrupt line, said second level on said downstream interrupt line is propagated to said upstream interrupt line so as to automatically generate an interrupt by said serial bus support circuit upon disconnection of said downstream peripheral device from said peripheral device.
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Abstract
A low power, single master, variable clock rate, daisy-chainable, serial bus connects a bus dispatch (master) to a chain of one or more daisy-chained peripheral devices (slaves). The bus has a bidirectional serial data line, a bidirectional clock line, unidirectional interrupt line, power and ground lines. Each peripheral device includes a plurality of serial bus support structures. For example, the serial bus support structures can include an interrupt generation circuit, a power-on circuit, and a wake-up interrupt generation circuit, and a wake-up interrupt propagation circuit.
95 Citations
51 Claims
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1. In a peripheral device, a serial bus support circuit comprising:
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a power supply line; a downstream interrupt line coupled to said power supply line wherein upon connection of a downstream peripheral device to said downstream interrupt line, said downstream interrupt line has a first level, and upon disconnection of said downstream peripheral device from said downstream interrupt line, said downstream interrupt line has a second level; an upstream interrupt line; and a bus interface circuit having a downstream interrupt in terminal coupled to said downstream interrupt line, and an upstream interrupt out terminal coupled to said upstream interrupt line wherein said bus interface circuit passes a signal on said downstream interrupt in terminal to said upstream interrupt out terminal so that upon said downstream peripheral device being disconnected from said downstream interrupt line, said second level on said downstream interrupt line is propagated to said upstream interrupt line so as to automatically generate an interrupt by said serial bus support circuit upon disconnection of said downstream peripheral device from said peripheral device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. In a peripheral device, a serial bus support circuit comprising:
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a power supply line; a downstream interrupt line; a pull-up resistive element connected to said downstream interrupt line; a first inverter having an input terminal connected to said downstream interrupt line; and
an output terminal;a second inverter having an input terminal connected to said output terminal of said first inverter; and
an output terminal;a bus interface circuit having a downstream interrupt in terminal connected to output terminal of said second inverter; and
an upstream interrupt out terminal;a third inverter having an input terminal connected to said upstream interrupt out terminal; and an output terminal; a fourth inverter having an input terminal connected to said output terminal of said third inverter; and
an output terminal;an upstream interrupt line connected to said output terminal of said fourth inverter; a wake-up interrupt propagation circuit having an input line connected to said downstream interrupt line; and
an output line connected to said upstream interrupt line; anda wake-up interrupt generation circuit having an output line connected to said upstream interrupt line.
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38. In a peripheral device, a wake-up interrupt propagation structure comprising:
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a power supply line; a downstream interrupt line; an upstream interrupt line; a bus interface circuit having a downstream interrupt in terminal coupled to said downstream interrupt line; and
an upstream interrupt out terminal coupled to said upstream interrupt line wherein said bus interface circuit passes a signal on said downstream interrupt in terminal to said upstream interrupt out terminal; anda gate having a first input terminal connected to said downstream interrupt line;
a second input terminal connected to said power supply line; and
an output terminal connected to said upstream interrupt linewherein upon a voltage on said power supply line having a first state, said gate passes a signal on said downstream interrupt line through said gate to said upstream interrupt line and so bypasses said bus interface circuit; and upon said voltage on said power supply line having a second state, said gate blocks passage of said signal on said downstream interrupt line through said gate to said upstream interrupt line. - View Dependent Claims (39, 40)
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41. In a peripheral device, a wake-up interrupt generation structure comprising:
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a power supply line; a downstream interrupt line; an upstream interrupt line; a bus interface circuit having a downstream interrupt in terminal coupled to said downstream interrupt line; and
an upstream interrupt out terminal coupled to said upstream interrupt line wherein said bus interface circuit passes a signal on said downstream interrupt in terminal to said upstream interrupt out terminal; anda microcontroller having a wake-up interrupt generation terminal; a gate having a first input terminal coupled to said wake-up interrupt generation terminal;
a second input terminal connected to said power supply line; and
an output line coupled to said upstream interrupt line;wherein upon a voltage on said power supply line having a first state, said gate passes a signal from said wake-up interrupt generation terminal through said gate to said upstream interrupt line; and upon said voltage on said power supply line having a second state, said gate blocks passage of said signal from said wake-up interrupt generation terminal through said gate to said upstream interrupt line. - View Dependent Claims (42, 43, 44, 45, 46, 47)
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48. In a peripheral device, a power on circuit comprising:
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a bus interface circuit having a peripheral power on terminal; a standby power supply line; a switch having a first terminal coupled to said standby power supply line;
a second terminal coupled to a reference voltage, and a third terminal coupled to said peripheral power on terminal whereinupon a first voltage being applied to said peripheral power on terminal by said bus interface circuit, said first switch terminal is connected to second switch terminal by said first voltage on said third terminal; and
otherwise said first switch terminal and said second switch terminal are disconnected;
an inverter having an input terminal connected to said first switch terminal; and
an output terminal connected to a power supply line for said peripheral device. - View Dependent Claims (49, 50)
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51. A method for powering up a peripheral device on a serial bus comprising:
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connecting a terminal of a bus interface circuit to a power supply circuit of said peripheral device wherein upon application of a first voltage level on said terminal said power supply circuit is off and upon application of a second voltage level on said terminal said power supply circuit is on; coupling said bus interface circuit to said serial bus; and issuing a power-on command over said serial bus to said bus interface circuit wherein in response to said power-on command, said bus interface circuit generates said second voltage level on said terminal.
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Specification