Concatenated two-wire data bus
Disclosed is a light module and a matching housing for a bus node. The light module is provided to be used in a data bus system for transmitting data for light-emitting components via a differential two-wire data bus. The data bus transmits data between a bus master and at least two bus nodes. The data bus is divided by the bus nodes into at least two two-wire data bus sections. The housing comprises at least two rows of connections arranged opposite each other. Each row comprises one negative supply voltage connection and one positive supply voltage connection, which are arranged to be connected in pairs without intersection. The two connections for each of the respective two-wire data bus sections are arranged between the connections for the supply voltages in each row. A light-emitting component is arranged in a recess of the housing.
1. A method for initializing a differential two-wire data bus between a bus master, and at least two bus nodes, the at least two bus nodes including one or more terminal bus nodes, wherein the two-wire data bus:
comprises a first one-wire data bus and a second one-wire data bus; and
is divided by the at least two bus nodes into at least two two-wire data bus sections, each of the at least two two-wire bus sections including a respective first one-wire data bus section and a respective second one-wire data bus section; and wherein each of the two-wire data bus sections is terminated by a respective terminal bus node;
the method comprising:
determining a new bus node address by the bus master;
storing the bus node address in a bus node address register of a bus node of interest, the bus node of interest being one of the at least two bus nodes, by the bus master, wherein the bus master and the bus node of interest are connected by one or more of the at least two two-wire data bus sections, and the bus node address register is one of:
a data register of a modified JTAG interface of the bus node of interest, or
a part of the data register of the modified JTAG interface of the bus node of interest, or
a part of an instruction register of the modified JTAG interface of the bus node of interest,
wherein the modified JTAG interface comprises a JTAG test controller comprising a state diagram corresponding to IEEE 1149 standard or a substandard of the IEEE 1149 standard; and
connecting one or more of the at least two two-wire data bus sections with one or more other of the at least two two-wire data bus sections by closing a transfer gate of the bus node of interest, whereby a further storage of a further bus node address in the bus node address register of the bus node of interest is prevented by the bus node of interest for as long as the transfer gate is closed.
2. The method according to claim 1 , further comprising:
storing an instruction to open the transfer gate in the instruction register or a transfer gate control register of the modified JTAG interface of the bus node of interest.
3. The method according to claim 1 , further comprising:
verifying a correct addressing of at least one of the at least two bus nodes by cyclic writing and reading a bypass register.
4. The method according to claim 3 , comprising:
determining a number of correctly addressable bus modes by the bus master;
comparing the number of correctly addressable bus nodes to a set number; and
triggering, by the bus master or a connected system, at least one signal or one measure as a function of the number of correctly addressable bus nodes.
5. A method for transmitting data after the initialization of the differential two-wire data bus according to claim 1 , comprising:
simultaneously transmitting a transmission address to all accessible bus nodes by writing transmission registers of each of the respective accessible bus nodes by the bus master having the transmission address, wherein the transmission register of each of the respective accessible bus nodes is the data register or a second part of the data register or a second part of the instruction register of the modified JTAG interface of the respective accessible bus node, and wherein the bus node address register is not respectively the second part of the data register or the second part of the instruction register of the respective accessible bus node;
comparing the transmission address in the transmission register in each of the respective accessible bus nodes to the bus node address in the bus node address register in the respective accessible bus node using a predetermined comparison algorithm;
activating a transmitting capability for the respective accessible bus node at times provided for that purpose, if the predetermined comparison algorithm of the comparison performed by the respective accessible bus node results in a level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node expected for a transmission permission; and
deactivating the transmitting capability for the respective accessible bus node, if the comparison algorithm of the comparison performed before by the respective bus node does not result in the level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node expected for the transmission permission.
6. A method for transmitting data after the initialization of the differential two-wire data bus according to claim 1 , comprising:
simultaneously transmitting a transmission address to all accessible bus nodes by writing transmission registers of each of the respective accessible bus nodes by the bus master having the transmission address, wherein the transmission register of each of the respective accessible bus nodes is the data register or a second part of the data register or a second part of the instruction register of the modified JTAG interface of the respective accessible bus node, and wherein the bus node address register is not respectively the second part of the data register or the second part of the instruction register of the respective accessible bus node;
comparing the transmission address in the transmission register in each of the respective accessible bus nodes to the bus node address in the bus node address register in the respective accessible bus node using a predetermined comparison algorithm;
activating a receiving capability of the respective accessible bus node for a content of predetermined data registers of the respective accessible bus node, if the predetermined comparison algorithm of the comparison performed before by the respective accessible bus node results in a level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node, expected for a transmission permission; and
deactivating the receiving capability of the respective accessible bus node for the content of predetermined data registers of the respective bus node, if the comparison algorithm of the comparison performed before by the respective bus node does not result in the level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node, expected for the transmission permission.
7. A method for transmitting data after the initialization of the differential two-wire data bus according to claim 1 , comprising:
simultaneously transmitting a transmission address to all accessible bus nodes by writing transmission registers of each of the respective accessible bus nodes by the bus master having the transmission address, wherein the transmission register of each of the respective accessible bus nodes is a data register or a second part of the data register or a second part of the instruction register of the modified JTAG interface of the respective accessible bus node, and wherein the bus node address register is not respectively the second part of the data register or the second part of the instruction register of the respective accessible bus node;
comparing the transmission address in the transmission register in each of the respective accessible bus nodes to the bus node address in the bus node address register in the respective accessible bus node using a predetermined comparison algorithm;
activating a receiving capability of the respective accessible bus node for a content of predetermined contents of the instruction register of the respective accessible bus node to allow predetermined instructions for an instruction decoder of the modified JTAG interface of the respective accessible bus node, if the predetermined comparison algorithm of the comparison performed before by the respective accessible bus node results in a level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node, expected for a transmission permission; and
deactivating the receiving capability of the respective accessible bus node for the content of the predetermined contents of the instruction register of the respective accessible bus node for suppressing the predetermined instructions for the instruction decoder of the modified JTAG interface of the respective accessible bus node, if the predetermined comparison algorithm of the comparison performed before by the respective accessible bus node does not result in the level of congruence of the bus node address stored in the bus node address register of the respective accessible bus node and the transmission address stored in the transmission register of the respective accessible bus node expected for the transmission permission.