Apparatus and method for an analog-to-digital converter having a programmable trigger level

• US 20070257829A1
• Filed: 08/21/2006
• Published: 11/08/2007
• Est. Priority Date: 05/08/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Lavery, Kevin P., Oak, Sunil S.
• Granted Patent: US 7,423,565 B2
• Time in Patent Office: Days
• US Class Current: 341/158
• CPC Class Codes: H03M 1/1225 using time-division multiplexing

Abstract

In response to a selected analog applied to the input terminal of an analog-to-digital converter, the digitized output signal is stored in a buffer/register. In making a comparison with a predetermined value, a second buffer/register stores either a preselected value or a second digitized signal. A comparator is coupled to the first and the second buffer/register to provide the result of a comparison. In this manner, the central processing unit is not involved in the comparison testing procedure.

Claims

1. Apparatus for comparing a digitized first signal with a second signal, the apparatus comprising:

an analog-to-digital converter, the analog-to-digital converter digitizing a first signal;

a first buffer/register coupled to the analog-to-digital converter, the first buffer/register storing the digitized first signal;

a second buffer/register storing a digitized second value; and

a comparator having first input terminal coupled to the first buffer/register, the comparator having a second input terminal coupled to the second buffer/register, the output terminal of the comparator providing comparison between the first and second signals.

2. The apparatus as recited in claim 1 wherein the output signal of the comparator is an interrupt signal.

3. The apparatus as recited in claim 1 further comprising;

a control unit, and

a multiplexer, the multiplexer coupling a plurality of input signals to an input terminal of the analog-to-digital converter, the control unit providing control signals to the multiplexer determining which input signal is coupled to the analog-to-digital converter input terminal.

4. The apparatus as recited in claim 3 further comprising a switch coupled between the output terminal of the analog-to-digital converter and at least two of the first buffer/registers and the second buffer registers, the control unit applying signals to the switch determining to which buffer register unit the output terminal of the analog-to-digital converter is coupled.

5. The apparatus as recited in claim 1 wherein the digitized second signal has preselected value.

6. The apparatus as recited in claim 1 wherein the second buffer/register is coupled to an output terminal of the analog-to-digital converter, the second buffer/register storing digitized value of a second signal.

7. The apparatus as recited in claim 1 further comprising:

a first mask coupled between the first buffer register and the first input terminal of the comparator; and

a second mask coupled between the second buffer/register and the second input terminal of the comparator.

8. A method of providing a signal defining a relationship between a first signal and a second signal, the method comprising:

digitizing a first signal;

storing the digitized first signal in a first buffer/register;

storing a digitized second signal in a second buffer/register; and

comparing the first signal and the second signal by a comparator.

9. The method as recited in claim 8 further comprising masking at least one of the first and the digitized signal.

10. The method as recited in claim 8 comprising digitizing the first signal by an analog-to-digital converter.

11. The method as recited in claim 8 wherein the second signal was digitized by the analog-to-digital converter.

12. The method as recited in claim 8 further comprising generating an interrupt signal determined by the comparing of the first and the second signals.

13. Apparatus for comparing a first signal and a first value, the apparatus comprising:

an analog-to-digital converter, the analog-to-digital converter converting an analog input signal to a digitized output signal;

a plurality of first buffer/registers;

a switch unit coupled between an output terminal of the analog-to-digital converter and the plurality of buffer/registers;

a control unit, the control unit determining to which buffer/register the output terminal of the analog-to-digital converter is coupled;

a plurality of second buffer/registers, each second buffer/register associated with a second/buffer register; and

a comparator coupled to each first buffer/register, second buffer pair, the comparator generating a preselected output signal when the contents of a buffer/register pair have a predefined relationship.

14. The apparatus as recited in claim 13 wherein the output signal of a comparator is an interrupt signal.

15. The apparatus as recited in claim 13, further comprising a multiplexer, the multiplexer coupling one of a plurality of input to an input terminal of the analog to digital converter in response to control signals from the control unit.

16. The apparatus as recited in claim 13 further comprising mask units coupled between the buffer/register units and the comparator.