Serial I/O device identifies itself to a computer through a serial interface during power on reset then it is being configured by the computer

• US 5,634,074 A
• Filed: 05/07/1993
• Issued: 05/27/1997
• Est. Priority Date: 05/07/1993
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Lynch, John, Nichols, James B., Devon, Mark
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Luu, Le Hien
• Application Number:
  US08/059,598
• Time in Patent Office: 1,481 Days
• Field of Search: 395/275, 395/325, 395/285, 395/830, 395/828, 395/823, 395/829, 370/60, 370/56, 340/825.52, 364/514
• US Class Current: 710/8
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices
• CPC Class Codes: G06F 15/177 Initialisation or configuration control processor initialisation G06F9/4405
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers

Abstract

A self-configuring startup procedure for communications devices, including telecommunications adapters, provides unambiguous identification of the telecommunications adapter, or other communications device, connected to a serial port. The procedure does not interfere with the operation of other existing I/O devices that might be connected to the serial port, such as network, MIDI, or other serial I/O devices. The I/O device is connected to a computer through a serial interface and a serial link. When the I/O device exits a reset state, the I/O device sends across the serial link to the computer a "beacon" signal identifying the I/O device. In particular, during the beacon phase, the I/O device communicates identification and configuration parameters. Preferably, the beacon phase may be instigated by the computer using the same serial-link communications channel.

Claims

1. In a system comprising a computer and an I/O device connected to the computer through a serial interface by a serial cable no more than a few feet in length, a method of identifying the I/O device, comprising the steps of:

in response to at least one of a power-up reset signal and a control signal from the computer, sending from the I/O device to the computer a beacon signal comprising a sequence of bytes identifying the I/O device; and

in response to the beacon signal, determining within the computer a manner of interaction of the computer with the I/O device.

2. The method of claim 1 wherein the I/O device is a communications pod, and the beacon signal identifies a type of the communications pod from among possible types of communications pods including telephony and LAN telecommunications pods.

3. The method of claim 1 wherein the beacon signal is sent with asynchronous framing.

4. The method of claim 3 wherein the beacon signal is sent at a predetermined low speed.

5. The method of claim 3 wherein the beacon signal is sent to the computer in accordance with a clock signal provided to the computer from the I/O device.

6. The method of claim 1 wherein said control signal from the computer comprises a pulse on a hardware control line.

7. The method of claim 1 wherein said control signal comprises at least one byte of data sent from the computer to the I/O device.

8. The method of claim 1, comprising the further step of:

in response to the beacon signal, sending from the computer to the I/O device a beacon acknowledge signal identifying a type of the serial interface.

9. The method of claim 8, comprising the further step of:

in response to the beacon acknowledge signal, sending from the I/O device to the computer a beacon completion signal.

10. The method of claim 8, wherein the beacon acknowledge signal further includes configuration information.

11. The method of claim 10 wherein the beacon acknowledge signal indicates to the I/O device the maximum data speed that the computer can support.

12. The method of claim 10 wherein the beacon acknowledge signal indicates the maximum frame size, from I/O device to computer, that the computer can support.

13. The method of claim 10 wherein the beacon acknowledge signal indicates the maximum frame size, from computer to I/O device, that the computer can support.

14. The method of claim 10 wherein the beacon acknowledge signal indicates a computer receive mode from among possible receive modes including a polled receive mode and a DMA receive mode.

15. The method of claim 10 wherein the beacon acknowledge signal indicates an expected I/O device receive mode from among possible receive modes including a polled receive mode and a DMA receive mode.

16. The method of claim 8, comprising the further step of:

in response to the beacon acknowledge signal, sending from the I/O device to the computer a beacon completion signal indicating whether an error has occurred, including whether an incompatibility exists between the computer and the I/O device.

17. The method of claim 16 wherein the beacon completion signal indicates to the computer the actual data speed that the I/O device will use to send data to the computer.

18. The method of claim 16 wherein the beacon acknowledge signal further indicates a maximum frame size, from I/O device to computer, that both the I/O device and the computer can support.

19. The method of claim 16 wherein the beacon acknowledge signal further indicates the maximum frame size, from computer to I/O device, that both the I/O device and the computer can support.