The EdSim51 Beginner's Guide to the 1. 5 The Program Status Word. Every microcontroller contains flags that be used for testing the outcome of an. Instructions are coloured blue, assembler directives (such as ORG, USING, etc) .. For details on how to communicate with the module, see HDpdf and. This book, titled EdSim51's Guide to the , is now available from Amazon. com. Read a sample chapter (PDF) for free. Purchase the book from: Amazon. com.
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The following installation instructions are for users running Windows or Ubuntu. However, the EdSim51DITM Simulator, because it is JavaTM based, should run. The user can set the number of instructions executed between updates to the simulator GUI by selecting a . A full explanation of the LCD Module: HD pdf. User Manual 3) Download computerescue.infoom/simulator/edsim51di. zip computerescue.info
This is done by sending the appropriate Function Set instruction see instruction set below. Why send Function set twice? If the correct instruction is sent with DL - on DB4 - set to zero, indicating 4-bit - see below , then the module 'knows' it is being set to 4-bit operation and it reads instructions and data in two 4-bit nibbles from then on.
Because it reads the high nibble first, the Function set high nibble must be sent again, followed by the low nibble. For more information, see pages 39 and 42 of HD The example on page 42 is for a 1-line display, but it nonetheless explains clearly how to initialise and communicate with the module in 4-bit mode. See below. Function Set Incorrectly: The programmer must set the module to 2-line, 5 X 8 font. The simulation of the HD is implemented for 2-line, 5 X 8 font only.
However, the programmer is still expected to write the code that sets the module in this mode.
EdSim51 - Example Programs
If the mode is not set correctly, an error message stating such is displayed, as shown here. The above diagram shows a 4 X 4 keypad - 16 switches configured in 4 columns and 4 rows. In the default state all switches open there is no connection between the rows and columns.
When a switch is pressed a connection between the switch's row and the switch's column is made. Keypad Decoder Many keypads are built with an onboard decoder that scans the keypad and, if a key is pressed, returns a number identifying the key.
Alternatively, a keypad decoder chip can be downloadd separately and interfaced with a keypad. The diagram below shows a 4 X 4 keypad interfaced with such a decoder.
Obviously, the outputs from the decoder don't need to go to the LSBs of P1, nor does the data available line DA need to be connected to the external 0 interrupt line. However, the above configuration is one way of interfacing a 4 X 4 keypad decoder to the The decoder has 8 inputs; the 4 X inputs are connected to the 4 keypad columns while the Y inputs are connected to the 4 keypad rows. Not shown in the diagram are pins for connecting capacitors to the decoder.
These capacitors govern the rate at which the keypad is scanned.
When a key is pressed the 4-bit code for the key there are 16 keys, therefore there are codes to in binary appears on the four output lines and in this case will appear on the 4 LSBs of P1 and the data available line DA goes LOW. If connected to an external interrupt line in this case, the INT0-bar line the microcontroller will be interrupted when a key is pressed.
The decoder chip takes care of switch debounce, therefore the programmer is freed from this responsibility, which is an advantage of using a decoder chip. Software Decoder The above decoder function can be implemented in software.
The keypad could be interfaced with the as detailed below.
With the above configuration, an interrupt is generated on the INT0-bar line when a key is pressed. We will deal with how this works in a moment. Firstly, let's see how the keyboard is scanned. The steps are:. The choices are: update the screen after every executed instruction, after , , 10, or 50, executed instructions.
Or, if none of these options is appropriate, the user can type in a number, then hit Enter.
The update frequency may be changed while a user's program is running. The Assembly Code Panel A simple assembly program is shown in the assembly code panel to the left. This program runs in a continuous loop, displaying the numbers 0 to 9 and back to 0 on the first 7-segment display.
A snapshot of its execution is shown to the right.
New Book EdSim51 s Guide to the core of the popular 51 series of 8-bit microcontrollers
When the background of the assembly code text area is white is it editable. The programmer can write code directly here, or can load a program from file using the Load button dealt with in the next section. Either way, the program will first be assembled.
If an error in the code is discovered, a message is displayed in the message box above the assembly code with a red background and the line with the error is highlighted within the code in red. If the code assembles without errors the text area's background changes to light grey. The code cannot be edited at this point.
If you want to go back to editing your code, simply click on the Reset button. Source code window a bit small? Read about the source pane unlocker below. Source Pane Unlocker The simulator was designed so that everything is visible on the screen at the same time - the internal registers, the source code, the peripherals, etc. However, this means the code pane is quite small. But it can be expanded.
EdSim51 - Notes on the
Read more. Load and Save The user can write code directly into the text box when it is in edit mode, or an existing program can be loaded from a file using the Load button. Similarly, code in the text box can be saved to file using the Save button. There are two file types handled.
The first is plain-text. Assembly programs are saved as regular plain-text files often called text-only and usually with. By default, this is the format used when saving your source code in the EdSim51 Simulator. The other file type is Intel HEX. Find out more on loading and saving Intel HEX files.
EdSim51 - User's Guide
To make the simulator more user-friendly, the last directory accessed either through loading a file or saving a file will be remembered.Update Freq. This gives the user access to all the 's registers and data memory. If the mode is not set correctly, an error message stating such is displayed, as shown here.
When the background of the assembly code text area is white is it editable. There are two file types handled.