Posts by Farahat

Using serial peripherals In Part E we consider how two powerful and influential serial communication protocols (‘I2C’ and ‘SPI’) may be utilized in applications with a time-triggered architecture. Use of these protocols has two main advantages: ● They are designed to allow microcontrollers to be linked to a wide range of different peripherals – memory, […]
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Example: Displaying elapsed time on an LCD This example displays elapsed time on an LCD character panel (Listings 22.1 to 22.3). Hardware The required hardware is shown in Figure 22.2. Software
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Example: LCD and keypad In this example we demonstrate a combined LCD–keypad interface (Figure 22.4).
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Example: Displaying elapsed time on a multiplexed (4-digit) LED display A common use for LED displays is to display the time. This simple example demon- strates the display of elapsed time on four multiplexed LEDs. The code is written for a standard 8051 (8052) device. The required hardware is illustrated in Figure 21.6. The key […]
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Introduction Many embedded applications contain user interfaces assembled from multi-segment LED displays. In this chapter, we consider how such displays may be interfaced to the 8051 family of microcontrollers. Mx led display Context ● You are developing an embedded application using one or more members of the 8051 family of microcontrollers. ● The application has […]
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Lcd character panel Context ● You are developing an embedded application using one or more members of the 8051 family of microcontrollers. ● The application has a time-triggered architecture, constructed using a scheduler. ● You are creating the user interface for your application. Problem How do you connect an LCD-based ‘character panel’ display to your […]
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Hardware resource implications All the examples here require the use of a scheduler. The main resource implication is that, to update (say) four digits, you need a scheduler with a tick interval of around 5 ms. This is not usually a limiting factor. Overall, the LED update code will consume only around 1% of the […]
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Introduction We considered the creation of LED-based user interfaces in Chapter 21. Here we are concerned with the use of liquid crystal displays (LCDs) in such interfaces. Unlike LEDs, LCDs are based on passive display technology: this means that LCDs control the passage of light rather than emitting light. This fact directly contributes to the […]
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Hardware resource implications While it does not require on-chip facilities (such as timers etc.), the keypad scanning process imposes both a CPU and memory load. Reliability and safety issues Keypad scanning is a software-based technique, closely related to SWITCH INTERF ACE ( SOFTW ARE ) [page 399]. In a hostile environment, use of a keypad […]
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Example: Using a dedicated baud rate generator As we noted in ‘Solution’, some 8051 microcontrollers have a timer dedicated to baud rate generation. This can be a useful facility, since it leaves us (usually) with three free timers for use in the scheduler, creation of delays and so on. In this example, we present an […]
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