The PCA9539; PCA9539R is a 24-pin CMOS device that provides 16 bits of GeneralPurpose parallel Input/Output (GPIO) expansion with INTERRUPT and reset forI2C-bus/SMBus applications and was developed to enhance the NXP Semiconductorsfamily of I2C-bus I/O expanders. I/O expanders provide a simple solution when additionalI/O is needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc.
The PCA9544A provides 4 INTERRUPT inputs, one for each channeland one open drain INTERRUPT output. When an INTERRUPT is generated byany device, it will be detected by the PCA9544A and the INTERRUPToutput will be driven LOW. The channel need not be active fordetection of the INTERRUPT. A bit is also set in the control byte.Bits 4 – 7 of the control byte correspond to channels 0 – 3 of thePCA9544A, respectively. Therefore, if an INTERRUPT is generated byany device connected to channel 2, the state of the INTERRUPT inputs isloaded into the control register when a read is accomplished.Likewise, an INTERRUPT on any device connected to channel 0 wouldcause bit 4 of the control register to be set on the read. The mastercan then address the PCA9544A and read the contents of thecontrol byte to determine which channel contains the devicegenerating the INTERRUPT. The master can then reconfigure thePCA9544A to select this channel, and locate the device generatingthe INTERRUPT and clear it. The INTERRUPT clears when the deviceoriginating the INTERRUPT clears.
The PCA9542A is a 1-of-2 bidirectional translating multiplexer, controlled via the I2C-bus.The SCL/SDA upstream pair fans out to two SCx/SDx downstream pairs, or channels.Only one SCx/SDx channel is selected at a time, determined by the contents of theprogrammable control register. Two INTERRUPT inputs, INT0 and INT1, one for each of theSCx/SDx downstream pairs, are provided. One INTERRUPT output, INT, which acts as anAND of the two INTERRUPT inputs, is provided.
The Philips family of Multiplexers and Switches consists of bi-directional translating switches controlled via the I2C or SMBus to fan out an upstream SCL/SDA pair to 2, 4 or 8 downstream channels of SCx/SDx pairs. The Multiplexers allow only one downstream channel to be selected at a time, while the Switches allow any individual downstream channel or combination of downstream channels to be selected, depending on the content of the programmable control register. Once one or several channels have been selected, the device acts as a wire, allowing the master on the upstream channel to send commands to devices on all the active downstream channels, and devices on the active downstream channels to communicate with each other and the master. External pull-up resistors are used to pull each individual channel up to the desired voltage level. Combined INTERRUPT output and hardware reset input are device options that are featured.
Internal INTERRUPTs are used to respond to asynchronous requests from a certain part of themicrocontroller that needs to be serviced. Each peripheral in the TriCore as well as theBus Control Unit, the Debug Unit, the Peripheral Control Processor (PCP) and the CPUitself can generate an INTERRUPT Request.So what is an external INTERRUPT?An external INTERRUPT is something alike as the internal INTERRUPT. The difference is that anexternal INTERRUPT request is caused by an external event. Normally this would be a pulseon Port0 or Port1, but it can be even a signal from the input buffer of the SSC, indicatingthat a service is requested.The User’s Manual does not explain this aspect in detail so this ApNote will explain themost common form of an external INTERRUPT request. This ApNote will show that there is aneasy way to react on a pulse on Port0 or Port1 and to create with this impulse an INTERRUPTService Request. Later in the second part of the document, you can find hints on how todebounce impulses to enable the use of a simple switch as the input device.Note: You will find additional information on how to setup the INTERRUPT System in theApNote “First steps through the TriCore INTERRUPT System” (AP3222xx)1. It would gobeyond the scope of this document to explain this here, but you will find selfexplanatoryexamples later on.
The Infineon TriCore provides an INTERRUPT System with a high safety standard. Thisdocument contains some instructions on how to initiate an INTERRUPT from an externaldevice. First it will show you how to trigger an INTERRUPT Service Request by an impulseon Port 0 or Port 1. Then in the second part of the document you can find hints how todebounce impulses to enable the use of a simple switch as input device.Authors: Thomas Bliem, CQ Nguyen / Infineon SMI MD Apps
This application note shows how to write an Inter Integrated Circuit bus driver (I²C) for the Philips P90CL301micro-controller.It is not only an example of writing a driver, but it also includes a set of application interface software routines toquickly implement a complete I²C multi-master system application.For specific applications the user will have to make minimal changes in the driver program. Using the drivermeans linking modules to your application software and including a header-file into the application sourceprograms. A small example program of how to use the driver is listed.The driver supports i.a. polled or INTERRUPT driven message handling, slave message transfers and multi-mastersystem applications. Furthermore, it is made suitable for use in conjunction with real time operating systems, likepSOS+.
This application note demonstrates how to write an Inter Integrated Circuit bus driver (I2C) for the XA-S3 16-bitMicrocontroller from Philips Semiconductors.Not only the driver software is given. This note also contains a set of (example) interface routines and a smalldemo application program. All together it offers the user a quick start in writing a complete I2C system applicationwith the PXAS3x.The driver routines support INTERRUPT driven single master transfers. Furthermore, the routines are suitable foruse in conjunction with real time operating systems.
The MC68HC05K0 is a low cost, low pin countsingle chip microcomputer with 504 bytes of userROM and 32 bytes of RAM. The MC68HC05K0 isa member of the 68HC05K series of devices whichare available in 16-pin DIL or SOIC packages.It uses the same CPU as the other devices in the68HC05 family and has the same instructions andregisters. Additionally, the device has a 15-stagemulti-function timer and 10 general purposebi-directional I/0 lines. A mask option is availablefor software programmable pull-downs on all ofthe I/O pins and four of the pins are capable ofgenerating INTERRUPTs.The device is ideally suited for remote-controlkeyboard applications because the pull-downs andthe INTERRUPT drivers on the port pins allowkeyboards to be built without any externalcomponents except the keys themselves. There isno need for external pull-up or pull-down resistors,or diodes for wired-OR INTERRUPTs, as these featuresare already designed into the device.
