Patent US5199105A successfully refreshed from Google Patents.
US5199105A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Universal asynchronous receiver/transmitter
Assignee: National Semiconductor Corp
•
Filing: 1991-08-15
•
Granted: 1993-03-30
•
Expires: 2011-08-15
Abstract
Abstract Data characters to be transferred from a peripheral device to a central processing unit are serially shifted into the receiver shift register of a universal asynchronous receiver/transmitter (UART). A multiple byte first-in-first-out memory stores a plurality of data characters received by the shift register. The UART checks the status of each data character stored in the FIFO to determine whether it will trigger an exception, A bytes till exception register indicates the number of data characters remaining in the FIFO until an exception is encountered. Then, upon request by the CPU, the UART provides the count of consecutive valid data characters from the top of the FIFO to the first exception, eliminating the need to check status on every transferred byte. Each of the multiple channels of the UART includes an Initialization Register. Setting the appropriate bit Initialization Register of any UART channel allows concurrent writes to the same selected register in each channel's register set. This function reduces initialization time for all of the common parameters that are loaded into each channel's registers. The UART implements a methodology which allows for the processing of any control characters or errors received by the UART during while internal and/or external FIFOs are being used.
Inventors
- 👤 Martin S. Michael
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:19
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/14; G06F13/20; G06F13/28; G06F13/38
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
162 words
A data processing system comprising: (a) a data processing system having a direct memory access unit associated therewith for transferring data characters from a system memory of the data processing system to a data communications device utilizing the direct memory access unit; (b) a data communications device comprising (i) transmitter memory means having storage locations for a plurality of data characters received by the data communications device from the system memory; (ii) means for determining whether the transmitter memory means is empty; (iii) means for establishing a count of the number of data characters that are to be transferred from the system memory to the data communications device utilizing the direct memory access unit; (iv) means for enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the data communications device; and (v) means for transferring the number of data characters to the data communications device utilizing the direct memory access unit.
Claim 2
Dependent Claim
162 words
A data processing system comprising: (a) a data processing system having a direct memory access unit associated therewith for transferring data characters from a system memory of the data processing system to a data communications device utilizing the direct memory access unit; (b) a data communications device comprising (i) transmitter memory means having storage locations for a plurality of data characters received by the data communications device from the system memory; (ii) means for determining whether the transmitter memory means is empty; (iii) means for establishing a count of the number of data characters that are to be transferred from the system memory to the data communications device utilizing the direct memory access unit; (iv) means for enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the data communications device; and (v) means for transferring the number of data characters to the data communications device utilizing the direct memory access unit.
Claim 3
Dependent Claim
199 words
A data processing system for transferring data characters from a data communications device to the system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the data communication device including receiver memory means having storage locations for a plurality of data characters received by the data communications device from a peripheral system for transfer to the system memory, the data processing system comprising: (a) means for maintaining a count of the number of data characters available for transfer from the receiver memory means before an exception is encountered; (b) means for establishing a trigger level for the receiver memory means; (c) means for initiating the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit when the receiver memory means trigger level is reached; and (d) means for continuing the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit until either an exception is encountered or until the number of valid data characters remaining to be transferred is less than the width of the data bus of the data processing system.
Claim 4
Dependent Claim
199 words
A data processing system for transferring data characters from a data communications device to the system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the data communication device including receiver memory means having storage locations for a plurality of data characters received by the data communications device from a peripheral system for transfer to the system memory, the data processing system comprising: (a) means for maintaining a count of the number of data characters available for transfer from the receiver memory means before an exception is encountered; (b) means for establishing a trigger level for the receiver memory means; (c) means for initiating the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit when the receiver memory means trigger level is reached; and (d) means for continuing the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit until either an exception is encountered or until the number of valid data characters remaining to be transferred is less than the width of the data bus of the data processing system.
Claim 5
Independent Claim
141 words
A method of transferring data characters from the system memory of a data processing system having a direct memory access unit associated therewith to a data communications device utilizing the direct memory access unit, the data communications device including transmitter memory means having storage locations for a plurality of data characters received by the data communications device from the system memory, the method comprising: (a) determining whether the transmitter memory means is empty; (b) establishing a count of the number of data characters that are to be transferred from the system memory to the data communications device; (c) enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the data communications device; and (d) transferring the number of data characters to the data communications device utilizing the direct memory access unit.
Claim 6
Independent Claim
141 words
A method of transferring data characters from the system memory of a data processing system having a direct memory access unit associated therewith to a data communications device utilizing the direct memory access unit, the data communications device including transmitter memory means having storage locations for a plurality of data characters received by the data communications device from the system memory, the method comprising: (a) determining whether the transmitter memory means is empty; (b) establishing a count of the number of data characters that are to be transferred from the system memory to the data communications device; (c) enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the data communications device; and (d) transferring the number of data characters to the data communications device utilizing the direct memory access unit.
Claim 7
Independent Claim
98 words
A method of transferring data characters from the system memory of a data processing system having a direct memory access unit associated therewith to an external storage unit have storage locations for a plurality of data characters, the method comprising: (a) determining whether the external storage unit is empty; (b) establishing a count of the number of data characters that are to be transferred from the system memory to the external storage unit; (c) enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the external storage unit.
Claim 8
Independent Claim
98 words
A method of transferring data characters from the system memory of a data processing system having a direct memory access unit associated therewith to an external storage unit have storage locations for a plurality of data characters, the method comprising: (a) determining whether the external storage unit is empty; (b) establishing a count of the number of data characters that are to be transferred from the system memory to the external storage unit; (c) enabling the direct memory access unit for direct transfer of the number of data characters from the system memory to the external storage unit.
Claim 9
Dependent Claim
72 words
A method as in claim 4 and further including the steps of issuing an interrupt to the data processing system when the number of data characters have been transferred from the system memory to the external storage unit; identifying the interrupt as indicating that the number of data characters has been transferred to the external storage unit; disabling the interrupt; reenabling the direct memory access unit to facilitate subsequent data character transfers;
Claim 10
Independent Claim
186 words
A method of transferring data characters from a data communications device to the system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the data communications device including receiver memory means having storage locations for a plurality of data characters received by the data communications device from a peripheral system for transfer to the system memory, the method comprising (a) maintaining a count of the number of data characters available for transfer from the receiver memory means before an exception is encountered; (b) establishing a trigger level for the receiver memory means; (c) initiating the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit when the receiver memory means trigger level is reached; (d) continuing the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit until either an exception is encountered or until the number of valid data characters remaining to be transferred is less than the width of the data bus of the data processing system.
Claim 11
Independent Claim
186 words
A method of transferring data characters from a data communications device to the system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the data communications device including receiver memory means having storage locations for a plurality of data characters received by the data communications device from a peripheral system for transfer to the system memory, the method comprising (a) maintaining a count of the number of data characters available for transfer from the receiver memory means before an exception is encountered; (b) establishing a trigger level for the receiver memory means; (c) initiating the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit when the receiver memory means trigger level is reached; (d) continuing the transfer of data characters from the receiver memory means to the system memory utilizing the direct memory access unit until either an exception is encountered or until the number of valid data characters remaining to be transferred is less than the width of the data bus of the data processing system.
Claim 12
Dependent Claim
53 words
A method as in claim 6 wherein transfer of data characters continues until an exception is encountered, the exception being an empty receiver memory means, the method including the additional step of terminating all data character transfers from the receiver memory means until the trigger level of the receiver memory means is reached.
Claim 13
Dependent Claim
124 words
A method as in claim 7 wherein transfer of data characters continues until an exception is encountered, the exception being a line status error, the method including the following additional steps: (a) issuing an interrupt to the data processing system; (b) determining the type of interrupt; (c) determining the location of valid data in the receiver memory means; (d) determining the specific nature of the exception; (e) clearing the interrupt; (f) executing a service routine for the specific line status error interrupt; (g) clearing the receiver memory means; (h) executing a purge routine to eliminate the remaining incoming data associated with the data character that triggered the exception; and (i) requesting retransmissions of the data associated with the data character that triggered the exception.
Claim 14
Dependent Claim
102 words
A method as in claim 7 wherein transfer of data characters continues until an exception is encountered, the exception being a match between a data character received by the data communications device and preselected comparison information, the method including the following additional steps: (a) issuing an interrupt to the data processing system; (b) determining the type of interrupt; (c) determining the location of valid data characters in the receiver memory means; (d) identifying the matched data character; (e) reaching the first storage location in the receiver memory means, discarding the matched data character; and (f) executing an appropriate control character service routine.
Claim 15
Dependent Claim
58 words
A method as in claim 7 wherein transfer of data characters continues until the number of data characters remaining to be transferred is less than the width of the data bus, the method including the additional step of terminating transfers from the receiver memory means utilizing the direct memory access unit until the trigger level has been reached.
Claim 16
Dependent Claim
114 words
A method as in claim 7 wherein transfer of data characters continues until the number of data characters remaining to be transferred is less that the width of the data bus and data character transfers have been discontinued for a preselected timeout period, the method including the following additional steps: (a) issuing an interrupt to the data processing system; (b) identifying the interrupt and the number of valid data characters remaining to be transferred; (c) transferring the number of consecutive valid data characters remaining to be transferred; (d) enabling the direct memory access unit for subsequent data character transfers from the receiver memory means to the system memory utilizing the direct memory access unit.
Claim 17
Independent Claim
273 words
A method of transferring data characters from a data communications device to an external storage unit for further transfer to a system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the external storage unit having storage locations for storing a plurality of data characters received from the data communications device, the data communications device including an internal receiver memory means having storage locations for storing a plurality of data characters received by the data communications device from a peripheral system, the method comprising: (a) establishing a preselected number of data characters that may be transferred from the internal receiver memory means to the external storage unit utilizing the direct memory access unit; (b) establishing a trigger level for the internal receiver memory means that indicates that the internal receiver memory means is storing a predefined number of data characters; (c) initiating the transfer of data characters from the internal receiver memory means to the external storage unit utilizing the direct memory access unit when the number of data characters stored in the internal receiver memory means equals the trigger level; and (d) continuing the transfer of data characters from the internal receiver memory means to the external storage unit utilizing the direct memory access unit until either the preselected number of data characters has been transferred to the external storage unit or an exception is encountered by the data processing system or until the number of valid data characters remaining to be transferred from the internal receiver memory means is less than the width of the data bus of the data processing system.
Claim 18
Independent Claim
273 words
A method of transferring data characters from a data communications device to an external storage unit for further transfer to a system memory of a data processing system utilizing a direct memory access unit associated with the data processing system, the external storage unit having storage locations for storing a plurality of data characters received from the data communications device, the data communications device including an internal receiver memory means having storage locations for storing a plurality of data characters received by the data communications device from a peripheral system, the method comprising: (a) establishing a preselected number of data characters that may be transferred from the internal receiver memory means to the external storage unit utilizing the direct memory access unit; (b) establishing a trigger level for the internal receiver memory means that indicates that the internal receiver memory means is storing a predefined number of data characters; (c) initiating the transfer of data characters from the internal receiver memory means to the external storage unit utilizing the direct memory access unit when the number of data characters stored in the internal receiver memory means equals the trigger level; and (d) continuing the transfer of data characters from the internal receiver memory means to the external storage unit utilizing the direct memory access unit until either the preselected number of data characters has been transferred to the external storage unit or an exception is encountered by the data processing system or until the number of valid data characters remaining to be transferred from the internal receiver memory means is less than the width of the data bus of the data processing system.
Claim 19
Dependent Claim
84 words
A method as in claim 12 wherein transfer of data characters continues until the receiver memory means trigger level is reached, the method including the additional steps of (a) issuing an interrupt to the data processing system; (b) reading the number of characters that have been transferred to the external storage unit; (c) clearing the interrupt; (d) processing the data characters stored in the external storage unit; (e) enabling the direct memory access unit for subsequent data character transfers from the receiver memory means.
References Cited (Backward Citations)
US4159532A
Cited
US4355354A
Cited
US4346440A
Cited
US4368512A
Cited
US4240138A
Cited
EP0029800A1
Cited
EP0089440A1
Cited
EP0125561A2
Cited
US4807112A
Cited
US4823312A
Cited
US4949333A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-03-29 | 1996-09-28 | 1997-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-03-29 | 2000-09-28 | 2001-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-03-29 | 2004-09-28 | 2005-03-30 | $7700.00 | Window Closed / Lapsed |