WO2018178910A1

WO2018178910A1 - Multi-chip device with cascaded serial communication

Info

Publication number: WO2018178910A1
Application number: PCT/IB2018/052158
Authority: WO
Inventors: Karl Robert Ward
Original assignee: Rakon Limited
Priority date: 2017-03-29
Filing date: 2018-03-29
Publication date: 2018-10-04

Abstract

An electronic device structure and a cascaded serial communication scheme that make it possible to avoid pre-installation programming operations in devices comprising two or more integrated circuits. At least one of the integrated circuits has a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the output pin serial communication signals presented at the input pin.

Description

MULTI-CHIP DEVICE WITH CASCADED SERIAL COMMUNICATION

FIELD OF THE INVENTION

The present invention relates to electronic devices comprising two or more integrated circuits. BACKGROUND OF THE INVENTION

It is often the case that in devices comprising multiple (i.e., two or more) integrated circuits (ICs) the said ICs need to be programmed, or communicated with, "in situ", i.e., after the ICs have been installed into the device. In order to be able to utilize many of the known communication schemes for programming of, or communicating with, the ICs, the latter are required to have different "identifications", or different communication addresses, which in turn requires pre-installation programming operations to assign the individual addresses, particularly so when the two or more ICs are otherwise identical and as such respond to the same communication protocol.

The need for additional pre-installation programming operations is a drawback, as it increases manufacturing costs and makes stock management more difficult due to the need to track the inventory of ICs that have different pre-programmed addresses.

In some cases, the ICs are manufactured with programmed setup data relating to the main functions of the ICs, but that data has to be adjusted after the ICs have been installed into the composite device. Such situations can arise with various multi-chip device types; for example, the manufacturing processes of temperature compensated oscillator devices and oven controlled oscillator devices often require that the ICs comprising the temperature compensated oscillator devices or oven controlled oscillator devices are further programmed with programmable register values that are determined based on data obtained during the production test of fully assembled devices. Some of presently known communication schemes require the availability of dedicated individual IC communication pins such as individual Chip Select pins, which can be a problem in situations when the composite device's maximum pin count is limited .

The multitude of device pins and internal to the device communication bus connections can also present specific problems in certain special applications. For example, in heated electronic devices such as oven controlled oscillator devices comprising two or more application-specific integrated circuits (ASICs), multiple communication device pins and internal conductive connections increase the undesirable heat losses from the heated device to the outside world, thus increasing the overall power consumption by the device and reducing the effectiveness of its temperature control. SUMMARY OF THE INVENTION

In broad terms, the present invention provides an electronic device structure and a cascaded serial communication scheme that make it possible to (a) avoid pre-installation communication address programming operations in devices comprising two or more integrated circuits, and (b) minimize the overall device pin count and the number of internal communication bus connections.

In broad terms in a first aspect the invention comprises an electronic device comprising two or more integrated circuits, wherein at least one of the said two or more integrated circuits has a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the output pin serial communication signals presented at the input pin.

In broad terms in a second aspect the invention comprises a method of programming of, or communication with, an electronic device comprising two or more cascaded integrated circuits, that includes the step of putting at least one of the said cascaded integrated circuits into a mode wherein communication signals presented at its input pin are reproduced at its output pin.

In broad terms in a third aspect the invention comprises a method of manufacturing an electronic device that has a device input pin and a device output pin and comprises two or more integrated circuits, wherein at least two of the said two or more integrated circuits each have a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the serial communication output pin communication signals presented at the serial communication input pin, and wherein at least two of the said two or more integrated circuits are connected in a cascaded arrangement such that the communication output pin of each of the cascaded integrated circuits, except last integrated circuit of the cascaded arrangement, is connected to the communication input pin of a next integrated circuit in the cascaded arrangement, which method comprises not programming at least one of the two or more integrated circuits fully before installation into the electronic device, and post-installation communicating with, or programming of, at least one of the two or more cascaded integrated circuits by asserting serial communication commands onto the device's input pin.

The device structure and serial communication scheme offered by the present invention are facilitated when at least some of the two or more integrated circuits of the device are arranged so that:

(a) the integrated circuits are capable of communicating via a serial communication protocol that incorporates one or more address bits,

(b) at least one of the two or more integrated circuits can be communicated to in order to change its address,

(c) at least one of the said two or more integrated circuits has an input communication pin and an output communication pin and can be programmed into a mode wherein serial communication signals presented at the input pin are reproduced at the output pin.

In order to reduce the overall device pin count, the aforementioned input and output pins can be configured to carry out other input or output functions at times when communication with the ICs is not taking place.

The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described with reference to the accompanying figures in which :

FIG. 1 shows a possible structure of one of the two or more integrated circuits comprising the device of the present invention. FIG. 2 shows an example of an integrated circuit comprising the device of the present invention, wherein the pass through circuit is implemented as a controllable analog switch.

FIG. 3 shows an example of an integrated circuit comprising the device of the present invention, wherein the pass through circuit is implemented a controllable active buffer. FIG. 4 shows an example of a composite device of the present invention comprising two cascaded integrated circuits.

FIG. 5 shows an example of a composite device of the present invention comprising more than two cascaded integrated circuits. DETAILED DESCRIPTION OF EMBODIMENTS

A possible structure of one of the two or more ICs that comprise the device of the present invention and that can be individually programmed or communicated to post-installation into the composite device is shown in Fig. 1. The IC has an input serial communication pin Serial Input for receiving the incoming serial communication data stream, and an output serial communication pin Serial Output for outputting the serial communication output data stream. Besides the circuit block Main Functions Circuitry facilitating the main functionality of the IC, it also has a Memory Controller capable of processing the incoming serial communication data stream and generating a serial communication output data stream as requested by the incoming command, and a Pass Through Circuit that enables the incoming data stream to be reproduced at the Serial Output pin. The Pass Through Circuit is controlled by the Memory Controller; the pass through function can be either disabled or enabled by the Memory Controller, depending on the command received by the Memory Controller through the serial communication interface of the IC.

The Pass Through Circuit can be, for example, a controllable analogue switch, as shown in Fig. 2. When the switch is open, the pass through mode is not enabled, and the Serial Output pin will not have the signal at the Serial Input pin reproduced at the output. When the pass through switch is closed, it will pass through the serial communications data from the Serial Input pin to the Serial Output pin. Alternatively, the Pass Through Circuit can be implemented as a controllable active buffer as shown in Fig. 3. Other ways of implementing the pass through circuit are possible, and a person skilled in the art of electronic circuit design will be able to come up with alternative circuit implementations to achieve the ability to reproduce the incoming serial communication signals at the ICs serial output when the pass through mode is enabled. The ability of the IC to be configured in a pass through mode wherein the serial communication signals at the Serial Input pin are reproduced at the Serial Output pin is a key feature to enable the communication and programming method of the present invention. The IC can be designed to respond to incoming commands even in pass through mode, thus ena bling the user to control various aspects of the IC's functionality in pass throug h mode too.

Fig . 4 shows an example of a composite device comprising two a pplication-specific integrated circuits (ASICs), named ASIC A a nd ASIC B. Either or both ASICs can be structured as described above, a nd in example shown in Fig . 4 both ASICs are equipped with communications a nd mode facilities as described a bove. The ASICs may, in fact, be electronically (i.e., hardware-wise) identical, but in any case neither of the ASICs has been pre-prog rammed fully before their installation into the Composite Device, a nd for the purpose of serial communications both ASICs may initially have the same defa ult serial communication add ress. Both ASICs initially have pass through mode disabled . The two ASICs are cascaded so that the serial communication output pin of ASIC A is connected to the serial communication input pin of ASIC B. Using the method of post-installation communications and prog ramming offered by the present invention, both ASICs can be fully programmed after their installation into the composite device without the need for pre-installation progra mming of the ASICs to assign individual communication add resses (and therefore without the need to manage stocks of ASICs with different communication addresses assigned to them during pre-installation progra mming), and without the need for the integrated circuits to have individual Chip Select pins. An example of a method of the present invention that allows individual communications with, and prog ramming of, each ASIC is described below.

To setup communications, the communication address of ASIC A is cha nged by communicating with ASIC A using its defa ult communication address. This is possible since in both ASICs the pass through mode is at this stage disabled and therefore only ASIC A will be getting the address cha nge comma nd . Next, ASIC A is placed in a pass through mode.

Once the setup is complete, the ASICs have d ifferent communication addresses, and selective communications with either of the ASICs a re possible as follows.

To read from or write to ASIC A:

place ASIC B into pass through mode by asserting a corresponding serial communication command addressed to ASIC B's (default) address on the Device Input pin ; ASIC A, with its pass th rough mode enabled, will pass the comma nd through to ASIC B without reacting to it; take ASIC A out of pass through mode by asserting a corresponding serial communication command addressed to ASIC A's assigned address on the Device Input pin; and

use the assigned address of ASIC A to read from or write to ASIC A by asserting corresponding serial communication commands addressed to ASIC A's assigned address on the Device Input pin; ASIC B (with its pass through mode enabled) will pass the data read from ASIC A straight through to the Composite Device's output pin Device Output.

To read from or write to ASIC B:

- put ASIC A in pass through mode (if not enabled) by asserting a corresponding serial communication command addressed to the assigned ASIC A's address on the Device Input pin;

take ASIC B out of pass through mode (if pass through is enabled) by asserting a corresponding serial communication command addressed to ASIC B's assigned address on the Device Input pin; ASIC A, with its pass through mode enabled, will pass the command through to ASIC B without reacting to it;

send commands with the (default) address of ASIC B to read from or write to it; ASIC A will pass the commands through to ASIC B, and data read from ASIC B will appear at the Device Output pin of the Composite Device.

For the finished state, a pass through may be set in non-volatile memory of all ICs in the Composite Device.

In order to reduce the overall device pin count, the ASICs' input and output pins can be configured to carry out other input or output functions at times when communication with the ICs is not taking place. The number of cascaded integrated circuits in a composite device of the present invention is not limited to two; any number of appropriately structured and cascaded integrated circuits can be programmed or communicated to using the communication scheme offered by the invention. The composite device comprising more than two cascaded integrated circuit shown in Fig. 5 serves to further explain the concept. This Composite Device comprises multiple integrated circuits IC1, IC2, ... ICn, where (n) can be any number greater than 2. Upon their installation into the Composite Device, all (n) ICs have the same default address, and the pass through mode is disabled in all (n) ICs. To setup communications, the communication address of IC1 is changed to assign IC1 with a unique address by communicating with IC1 using its default communication address. This is possible because in all ICs the pass through mode is at this stage disabled and therefore only IC1 will be getting the address change command. Next, IC1 is placed in a pass through mode, and the communication address of the next cascaded integrated circuit (IC2) is changed to assign IC2 with a unique address in the cascade; this is possible because IC1, being in pass through mode, will pass the incoming serial communication command to IC2, and IC2 will be the only integrated circuit with the default address that will be getting the address change command. Next, IC2 is placed in pass through mode too. By continuing the process, all (n) integrated circuits can be arranged to have unique for the cascade communication addresses. Once that is done, selective communication with any one of the cascaded ICs is possible, i.e. any one of the cascaded ICs can be written to or read from, and any one of the cascaded ICs can be placed in or out of pass through mode. In order to write to a specific IC in the cascade, all of the ICs preceding it in the cascade will be put in pass through mode to ensure that the communication command will reach the target IC. In order to read from a specific IC, all of the ICs that follow it in the cascade will also be put in pass through mode so that the data read from the IC can be received at the Serial Output pin of the Composite Device.

In order to reduce the overall device pin count, the ICs' input and output pins can be configured to carry out other input or output functions at times when communication with the ICs is not taking place.

The IC structure and communication scheme offered by the present invention can be advantageously used in a wide variety of composite device types wherein a composite device comprises two or more ICs that need to be programmed "in-situ", i.e. after the ICs have been installed into the composite device. An example of a frequency control type device comprising two ASICs and utilizing the structure and communication scheme offered by the present invention is an Oven Controlled Oscillator wherein one of the two ASICs is utilized as a heating and temperature control component, whereas the other of the two ASICs facilitates the oscillator and, possibly, temperature compensation functionality. The two ASICs necessarily need to be programmed with data obtained post-installation of the ASICs and during the Oven Controlled Oscillator's production testing ; provided the two ASICs comprising the Oven Controlled Oscillator device are equipped with the serial communication data pass through ability, the communication and programming method of the present invention can be advantageously used. Another example of a frequency control type device comprising two ASICs and utilizing the structure and communication scheme offered by the present invention is a Temperature Compensated Oscillator wherein one of the ASICs contains electronics circuits of the oscillator and primary temperature compensation, whereas the second ASIC facilitates secondary compensation (or "post-compensation") functionality. In such a composite Temperature Compensated Oscillator device, both ASICs necessarily need to be programmed with data obtained post-installation of the ASICs and during production testing of the Temperature Compensated Oscillator device; provided the two ASICs comprising the device are equipped with the communication serial data pass through ability, the communication and programming method of the present invention can be advantageously used.

The applications of the structures and communication scheme offered by the present invention are not limited to Frequency Control devices, but can advantageously be used in any multi- chip device wherein the individual chips need to be programmed or communicated to after they have been installed into the device, and without the need for pre-installation programming of the chips to assign individual communication addresses.

The multi-chip devices implemented as per the present invention may be used in a variety of electronic apparatus; such apparatus include, but are not limited to, portable and stationary telecommunication equipment, high speed networking equipment, radio communication equipment, and navigation equipment.

Claims

An electronic device comprising two or more integrated circuits, wherein at least one of the said two or more integrated circuits has a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the output pin serial communication signals presented at the input pin.

An electronic device according to claim 1, wherein at least two of the said two or more integrated circuits have each a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the output pin serial communication signals presented at the input pin.

An electronic device according to claim 1 or claim 2, wherein at least two of the said two or more integrated circuits are cascaded so that the serial communication output pin of one of the cascaded integrated circuits is connected to a serial communication input pin of the next cascaded integrated circuits.

An electronic device according to any of claims 1 to 3, wherein at least two of the said two or more integrated circuits are structurally identical.

An electronic device according to any of claims 1 to 4, wherein at least one of the said two or more integrated circuits comprises a memory controller capable of processing an incoming serial communication data stream and generating a serial communication output data stream as requested by an incoming command, and a pass through circuit that enables the incoming data stream to be reproduced at the output pin.

An electronic device according to claim 5, wherein at least one of the said two or more integrated circuits are responsive to incoming commands in a pass through mode.

An electronic device according to any of claims 1 to 6, wherein the said device is a frequency control device.

A frequency control device according to claim 7, wherein the said device is an oven- controlled oscillator.

9. A frequency control device according to claim 7, wherein the said device is a temperature compensated oscillator.

10. A method of programming of, or communication with, an electronic device comprising two or more cascaded integrated circuits, that includes the step of putting at least one of the said cascaded integrated circuits into a mode wherein communication signals at its input pin are reproduced at its output pin.

11. A method of manufacturing an electronic device that has a device input pin and a device output pin and comprises two or more integrated circuits, wherein at least two of the said two or more integrated circuits each have a serial communication input pin, a serial communication output pin, and can be programmed to reproduce at the serial communication output pin communication signals presented at the serial communication input pin, and wherein at least two of the said two or more integrated circuits are connected in a cascaded arrangement such that the communication output pin of each of the cascaded integrated circuits, except last integrated circuit of the cascaded arrangement, is connected to the communication input pin of a next integrated circuit in the cascaded arrangement, which method comprises not programming at least one of the two or more integrated circuits fully before installation into the electronic device, and post- installation communicating with, or programming of, at least one of the two or more cascaded integrated circuits by asserting serial communication commands onto the device's input pin.

12. A method according to claim 11 wherein upon installation in the electronic device the cascaded integrated circuits have a same default communication address.

13. A method according to claim 11 or claim 12, wherein the said post-installation programming includes assigning a unique communication address to at least one of the cascaded integrated circuits.

14. A method according to any of claims 11 to 13, wherein the said post-installation programming of at least one of the cascaded integrated circuits includes placing all of the integrated circuits preceding the said one integrated circuit in a pass through mode.

15. A method according to any of claims 11 to 13, wherein the said post-installation programming of at least one of the cascaded integrated circuits includes placing all of the integrated circuits that follow the said one integrated circuit in a pass through mode.

16. A method according to any of claims 11 to 13, wherein the said post-installation programming of at least one of the cascaded integrated circuits includes placing all of the integrated circuits preceding the said one integrated circuit and all of the integrated circuits that follow the said one integrated circuit in a pass through mode.

17. An electronic apparatus comprising the device according to any of claims 1 to 9.