Patent Application
20100211336
1. Field of the Disclosure
The present disclosure relates generally to electronic devices, and more particularly to data processing devices.
2. Description of the Related Art
Very large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining a large number of components at a single IC package. The IC package can include a single IC die or can include more than one IC die. An IC package that contains more than one IC die is referred to as a multi-chip module (MCM). For example, a data processing device that includes two individual microprocessor IC die can be implemented by including the two individual microprocessor IC die at a single MCM. Each IC die is manufactured individually and each IC die is bonded to a substrate included at the MCM package. The MCM package substrate includes conductors that provide electrical connections between the pins of each IC die and between pins of the IC die and external interface pins of the MCM. The conductors can carry data signals and reference signals.
The pins of an IC die are conductive structures, such as metalized pads to which wires are bonded, metal bumps that are disposed at a portion of the surface of the IC die, and the like. The individual pins of the IC die and corresponding conductors included at the MCM substrate are bonded together to provide electrical connections. Packaging technology limits how physically small these electrical connections can be and therefore limits the number of individual pins that can be incorporated on a particular IC die. Therefore, the number of pins that can be physically disposed at an IC die can limit the number of circuit components that can be included at an individual IC die. Providing a signal interface to multiple IC die incorporated at an MCM is particularly difficult.
The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
A device and method are disclosed to provide a die-to-die communication link (DDCL) to facilitate the exchange of information of different types between two or more IC die included at a data processing device using a time-divided multiplexed protocol.
IC die 120 has a pin 1202 connected to conductor 140, a pin 1204 connected to conductor 142, and a pin 1206 connected to conductor 144. IC die 130 has a pin 1302 connected to conductor 144, a pin 1304 connected to conductor 142, and a pin connected to conductor 146. MCM 110 has an external interface pin 152 connected to conductor 140, an external interface pin 154 connected to conductor 142, and an external interface pin 156 connected to conductor 146. Therefore, pins at IC die 120 and IC die 130 are each connected to corresponding conductors, such as conductors 140, 142, and 144 at MCM 110 to provide an electrical connection between pins of the IC die and the conductors at MCM 110.
A MCM such as MCM 110 can include hundreds of individual conductors, and each conductor can conduct signals to and from pins included at IC die 120 and IC die 130, or between a pins at an IC die and external interface pins of MCM 110, such as pins 152, 154, and 156. An external interface pin at MCM 110 can serve as an input, an output, or a bidirectional interface to MCM 110. For example, in an embodiment conductor 142 can conduct a clock signal received at pin 154 and provide that signal to pin 1204 at IC die 120 and pin 1304 at IC die 130. External interface pin 152 can be an output of MCM 110 to conduct a memory address originating at IC die 120 to a memory device at data processing system 100. A common external interface pin at MCM 110 can function as an output for signals conducted from both IC die 120 and IC die 130 by using tri-state or open-collector style drivers at each of the IC die. IC die 120 and IC die 130 can include data processing devices such as microprocessor devices, peripheral interface devices, another type of data processing device, or a combination thereof.
IC die 120 and IC die 130 each includes a DDIC module to support the exchange of information between each IC die. One IC die, such as IC die 120, is designated to be a master device, and remaining IC die are designated as slave devices. The IC die designated as the master device can serve as an exclusive interface between MCM 110 and data processing system 100 for a particular class of information. The master device can relay information between data processing system 100 and a slave device. Designation of an IC die as a master device can be achieved by bonding a pin at each IC die to an appropriate voltage reference. For example, a master pin associated with the master device can be connected to a logic-high voltage reference, while the master pin associated with slave devices can be connected to a logic-low voltage reference. The master device can relay information received via external interface pins of MCM 110 to a slave device using the DDCL, and can forward information originating at a slave device and received via the DDCL to data processing system 100. Thus, each IC die of MCM 110 does not require dedicated connections to external interface pins at MCM 110 in order to communicate with the other portions of data processing system 100. Logic circuitry associated with arbitration for the use of a shared external interface pin by multiple IC die can thereby be eliminated.
For example, IC die 120 can be designated at a master device and IC die 130 can be designated as a slave device. Data processing system 100 can request the current operating temperature of IC die 130. Master IC die 120 receives the request via external interface pins at MCM 110 and uses DDIC 122 to transmit the request to DDIC 132 at slave IC die 130. Slave IC die 130 uses DDIC 132 to transmit the requested information back to DDIC 122 at master IC die 120. Master IC die 120 forwards the information to data processing system 100 via external interface pins at MCM 110. Master IC die 120 may further be designated as a master boot processor that is responsible for coordinating the proper initialization of slave devices. In one embodiment, master IC die 120 can use the DDCL to provide information to slave devices before the individual slave devices are configured to exchange information directly with an external memory device at data processing system 100.
Some requests originating outside MCM 110 can affect the timing of other communications between MCM 110 and data processing system 100. Such requests can be particularly problematic when they are received during a manufacturing test procedure because the test process can become non-deterministic. When a device such as MCM 110 is undergoing testing to verify that the manufactured device is fully functional, automatic test equipment (ATE) provides stimulus to external interface pins at MCM 110 and the ATE compares responses received at external interface pins of MCM 110 to expected responses. ATE typically requires that all responses be received at a precise and deterministic time. If an unexpected request is received at MCM 110 at a time that is non-deterministic relative to information being provided by the test procedure, responses from MCM 110 can be delayed, and the ATE may be unable to determine whether the device is functioning correctly.
For example, during testing, the ATE or other device may periodically request that IC die 130 provide temperature information from an on-die temperature sensor. Such a request can be issued at random times with respect to a test that is underway. In order to satisfy the request without disrupting the anticipated synchronous procession of the test, DDIC 122 and DDIC 132 use a time-divided multiplex protocol, which reserves particular time slots of the protocol for specific types of data. Thus, exchange of temperature information between IC die 120 and IC die 130 can take place during reserved time intervals so as not to interfere with other die-to-die communications. The DDCL can be used to exchange information between individual IC die to support a background task without interfering with the timing of a foreground task that is executing concurrently at each IC die.
DDIC 122, included at IC die 120, and DDIC 132, included at IC die 130, each receive reset signal RESET and clock signal CLKIN from external interface pins at MCM 110. DDIC 122 and DDIC 132 use clock signal CLKIN to synchronize transmission and reception of information conducted via nodes DMASTER and DSLAVE. Nodes DMASTER and DSLAVE each can conduct a four-bit signal, and are used to communicate information between DDIC 122 and DDIC 132. In one embodiment, signal CLKIN is a 200 MHz clock signal provided by data processing system 100. The arrival of signal CLKIN at DDIC 122 can be skewed relative to the arrival at DDIC 132 due to circuit and interconnect imbalances. DDICs 122 and 132 are typically designed to operate correctly when receiving a clock signal with a duty cycle from 40% to 60% to account for imbalance in the arrival time of signal CLKIN.
During the assertion of signal RESET, DDIC 122 and DDIC 132 set their corresponding outputs to a logic-low value. Following the de-assertion of signal RESET, an initialization procedure is performed at each of DDIC 122 and DDIC 132. At particular times after the de-assertion of signal RESET, a data transmitter at DDIC 122 can transmit a valid bit. The valid bit is conducted via node DMASTER to an associated data receiver at DDIC 132. A data receiver at DDIC 132 recognizes the valid bit as an indication that a predefined time-divided multiplex sequence has begun. Independently, a data transmitter at DDIC 132 can perform the same procedure to establish synchronization with a data receiver at DDIC 122. The initialization sequence is further described with reference to
DDIC 122 and DDIC 132 each has a local interface to communicate with logic modules at IC die 120 and IC die 130, respectively. DDIC 122 can exchange information with other logic modules at IC die 120 via interface DATA1, and DDIC 132 can exchange information with other logic modules at IC die 130 via interface DATA2. For example, IC die 120 can include individual logic modules, such as logic modules configured to support power management (PM) and side band interface (SBI) functions. Each of these modules at IC die 120 can communicate with a similar module at IC die 130 via the DDCL 200 using DDIC 122 and DDIC 132. DDIC 122 and DDIC 132 exchange information using a time-divided multiplexed protocol described in detail with reference to
High-speed interface HT is a Hyper Transport interface used to exchange information between IC die 120 and IC die 130, and between an IC die and data processing system 100. The HT interface is configured to support high-priority communications between individual data processing devices at data processing system 100, such as instructions and data information associated with a primary task being executed at IC die 120 and IC die 130. DDCL 200 can support exchange of information between IC die that is infrequent or of a relatively low priority compared to exchanges supported by the HT interface. Thus, the performance of the HT interface is not reduced as would be the case if bandwidth associated with the HT interface were reserved for the infrequent operations supported by DDCL 200.
SLOT0 is associated with miscellaneous data, and labeled “SS.” SLOT1 is primarily associated with power management information and is labeled “PM.” SLOT2 is primarily associated with side band interface information and is labeled “SBI.” SLOT3 is primarily associated with thermal data and is labeled “TD.” A greater or lesser number of time slots in each repeating set of time slots can be implemented to accommodate a different number of data types. Specific time slots can be associated with data types based on requirements of a particular data processing device.
Timing diagram 400 includes signal CLKIN that is used by each of DDIC 122 and 132 to synchronize the transmission and reception of data transmitted via DDCL 200. In one embodiment, DDIC 122 transmits data in response to the rising edge of clock signal CLKIN, and DDIC 132 receives and latches that data in response to the falling edge of clock signal CLKIN. Four bits of data are transmitted during each clock cycle and each bit of data is associated with a corresponding bit of signal DDOUT(3:0). Data that contains more than four bits of information is transmitted during subsequent cycles of clock signal CLKIN. Time slot SLOT0 in accordance with the specific embodiment disclosed has a duration corresponding to a single clock cycle. Time slots SLOT1 and SLOT2 each have a duration corresponding to two clock cycles, and time slot SLOT3 has a duration corresponding to three clock cycles. Each time slot is primarily associated with a particular data type.
Data is transmitted as a data stream where the first bit of each data type is preceded by a corresponding valid bit that is asserted when data of that data type is being transmitted. Data is transmitted in a little endian manner such that the least significant bit of each data type is transmitted first. Signal DDOUT(3:0) can represent data transmitted by either of DDIC 122 or DDIC 132, and conducted by either of interconnects DMASTER and DSLAVE at
Time slot SLOT0 is followed by time slot SLOT1. Time slot SLOT1 is allocated to the transmission of most of the bits of information corresponding to data type PM. Data type PM includes eight bits of information, and is preceded by a valid bit PM VALID 4504. For example, the valid bit associated with the PM data type, PM VALID 4504, is transmitted via signal DDOUT(0) and PM(0), PM(1), and PM(2) are transmitted via signal DDOUT(1), DDOUT(2), and DDOUT(3), respectively, during the same clock cycle. The second clock cycle included in time slot SLOT1 is used to transmit the next four bits of PM information via signal DDOUT(0), DDOUT(1), DDOUT(2), and DDOUT(3), respectively. The final bit of PM information, PM(7), is transmitted via signal DDOUT(0) during the first clock cycle of time slot SLOT2.
Time slot SLOT1 is followed by time slot SLOT2. Time slot SLOT2 is allocated primarily to the transmission of most of the bits of information corresponding to data type SBI. Data type SBI includes eight bits of information, and is preceded by a valid bit SBI VALID 4402. SB VALID 4402 is transmitted via signal DDOUT(1) during the first clock cycle of time slot SLOT1. SBI(0) and SBI(1) are transmitted via signal DDOUT(2) and DDOUT(3), respectively, during the same clock cycle. The second clock cycle included in time slot SLOT2 is used to transmit the next four bits of SBI information via signal DDOUT(0), DDOUT(1), DDOUT(2), and DDOUT(3), respectively. The final two bits of SBI information, SBI(6) and SBI(7), are transmitted via signal DDOUT(0) and DDOUT(1) during the first clock cycle of time slot SLOT3.
Time slot SLOT3 is primarily allocated to transmission of data corresponding to data type TDI. The valid bit associated with the TDI data type, TDI VALID 4302, is transmitted via signal DDOUT(2) during the first clock cycle of time slot SLOT3. In the particular example illustrated at
Even though information corresponding to more than one data type can be transmitted during a particular clock cycle, each bit of signal DDOUT(3:0) is reserved to represent one bit of one type of data for a particular time slot and clock cycle within that time slot. For example, the valid bit for data type SBI, SBI VALID 4402, is always transmitted via signal DDOUT(1) during the first clock cycle of time slot SLOT2. Time slot SLOT3 includes three clock cycles and is predominately associated with data type TDI, which includes nine bits of information. Time reference T4 corresponds to time reference T0 in so much as time slot SLOT0 immediately begins at time reference T4. The sequence of time slots SLOT0, SLOT1, SLOT2, and SLOT3 repeats every eight cycles of clock signal CLKIN.
DDCL 200 can support simultaneous transfer of information from master DDIC 122 to slave DDIC 132, and from slave DDIC 132 to master DDIC 122. Each of DDIC 122 and DDIC 132 includes a data transmitter and a data receiver, and the transmitter and receiver at a particular DDIC operate independently.
Before communication can commence via DDCL 200, the data receiver at each of DDIC 122 and 132 must be initialized so that it is synchronized to the corresponding data transmitter at DDIC 132 and 122, respectively. Each data transmitter independently issues an initial valid bit, SS VALID 4502, to the associated data receiver some time after signal RESET is de-asserted. Prior to sending the first valid bit, signal DDOUT(0) remains at an logic-low level. Receipt of the valid bit at a corresponding data receiver at a particular clock cycle indicates that that clock cycle represents the first cycle of time slot SLOT0. The eight clock-cycle repeating sequence begins and continues until signal RESET is again asserted. Each of DDIC 122 and DDIC 132 perform this initialization independently. Thus, the data receiver at DDIC 132 is synchronized to the data transmitter at DDIC 122, and the data receiver at DDIC 122 is synchronized to the data transmitter at DDIC 132. Data provided at DDOUT(3:1) associated with the initial valid bit SS VALID 4502 can be recognized as valid data. In another embodiment, the data associated with the initial valid bit SS VALID 4502 can be ignored.
The number of unique data types and the number of bits included in each data type illustrated at
The time-divided multiplexed protocol provided by DDCL 200 permits the exchange of information associated with random or asynchronous events to be interleaved with other device operations. For example, during a manufacturing test procedure ATE provides test stimulus to MCM 110, and IC die 120 and IC die 130 respond to the stimulus at a deterministic time. At the same time that the manufacturing test is underway, the ATE can issue a request for temperature information that is stored at a register at IC die 130. The request for thermal information is not associated with the prepared test stimulus. The request for temperature information is received at master IC die 120, and the request is relayed to slave IC die 130 via DDCL 200 during a time slot reserved for exchange of information of this data type. Slave IC die 130 transmits the requested temperature information to IC die 120 during an appropriate time slot, and master IC die 120 provides the information to the ATE via external interface pins of MCM 110. Because DDCL 200 reserves specific time slots for transferring temperature information, the manufacturing test procedure that is underway is not interrupted.
IC die 120 and IC die 130 each include two DDIC modules. The two DDIC modules at each IC die are instantiated on opposite edges of the IC die. The DDIC module can be enabled independently to allow separate connections between three or more IC die, or mutually exclusive of each other to facilitate a single connection between two or more die. For example, one of the two DDIC modules can be enabled and the other is disabled based on the relative physical location of the two die within MCM 110. For example, if IC die 120 is positioned above IC die 130 at MCM 110, DDIC 122, which is instantiated at the bottom edge of IC die 120 is enabled, and DDIC 124 that is instantiated at the top edge of IC die 130 is disabled. In a corresponding manner, DDIC 134 that is instantiated at the top edge of IC die 130 is enabled, and DDIC 132 that is instantiated at the bottom edge of IC die 130 is disabled. Thus, DDIC 122 and DDIC 134 are configured to provide a DDCL to exchange information between IC die 120 and IC die 130. Replicating the DDIC modules permits identical IC die to be used interchangeably for both IC die included at MCM 110. Furthermore, using an appropriate DDIC module can reduce the length of conductors included at MCM 110, and the congestion of the conductors. Thus, signal propagation delay associated with DDCL 200 is also reduced. In another embodiment, a portion of a DDIC module is replicated on opposite edges of the IC die and the two replicated portions share the remaining portion of the DDIC module.
Note that not all of the activities or elements described above in the general description are required, that a portion of a specific activity or device may not be required, and that one or more further activities may be performed, or elements included, in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed.
Also, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.
For example, DDIC 122 and DDIC 132 can include additional inputs and outputs (not shown) to transmit and receive signals used during the testing of DDIC 122 and DDIC 132. In a particular embodiment, ATE can configure DDIC 122 and DDIC 132 time reference be operating in a test mode and test information can be scanned into and out of each DDIC module using a Joint Test Action Group (JTAG) interface. Furthermore, information can be exchanged between DDIC 122 and DDIC 132 during a test procedure using the additional inputs and outputs.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.
