 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AT83C5103XXX-ICSAL Datasheet(PDF) 12 Page - ATMEL Corporation |
|
||||||||||||||||||||||||||||||
AT83C5103XXX-ICSAL Datasheet(HTML) 12 Page - ATMEL Corporation |
|
|
12 / 64 page  12 AT8xC5103 4134C–8051–09/04 Ports The AT8xC5103 has 3 I/O ports, port 1, port 3 and port 4. Except RST, and port 4, all port 1 and port 3 I/O port pins on the AT8xC5103 may be software configured to one of four types on a bit-by-bit basis, as shown in Table 2 These are: quasi-bi-directional (standard 80C51 port outputs), push-pull, open drain, and input only. Two configuration registers for each port choose the output type for each port pin. Port Types Quasi-Bi-directional Output Configuration The default port output configuration for standard AT8xC5103 I/O ports is the quasi-bi- directional output that is common on the 80C51 and most of its derivatives. This output type can be used as both an input and output without the need to reconfigure the port. This is possible because when the port outputs a logic high, it is weakly driven, allowing an external device to pull the pin low. When the pin is pulled low, it is driven strongly and able to sink a fairly large current. These features are somewhat similar to an open drain output except that there are three pull-up transistors in the quasi-bi-directional output that serve different purposes. One of these pull-ups, called the ‘very weak’ pull-up, is turned on whenever the port latch for the pin contains a logic 1. The very weak pull-up sources a very small current that will pull the pin high if it is left floating. A second pull- up, called the ‘weak’ pull-up, is turned on when the port latch for the pin contains a logic 1 and the pin itself is also at a logic 1 level. This pull-up provides the primary source cur- rent for a quasi-bi-directional pin that is outputting a 1. If a pin that has a logic 1 on it is pulled low by an external device, the weak pull-up turns off, and only the very weak pull- up remains on. In order to pull the pin low under these conditions, the external device has to sink enough current to overpower the weak pull-up and take the voltage on the port pin below its input threshold. The third pull-up is referred to as the ‘strong’ pull-up. This pull-up is used to speed up low-to-high transitions on a quasi-bi-directional port pin when the port latch changes from a logic 0 to a logic 1. When this occurs, the strong pull-up turns on for a brief time, two CPU clocks, in order to pull the port pin high quickly. Then it turns off again. The quasi-bi-directional port configuration is shown in Figure 3. PxM1.y BIt PxM2.y Bit Port Output Mode 0 0 Quasi bi-directional 0 1 Push-pull 1 0 Input Only (High Impedance) 1 1 Open Drain |
Similar Part No. - AT83C5103XXX-ICSAL |
|
Similar Description - AT83C5103XXX-ICSAL |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
