Readers should also study the page data sheet that covers the devices,. Microchip code DSA (see later). The following EPE subject material is. Note: The datasheet of PIC16FA Microcontroller and more detailed Features can be found at the bottom of this page. (Consult Sections of the 16F87x Data Sheet and of the Midrange Reference Manual for more detail.) Inside the 16F87x’s PWM module, the period is.

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HVP is always available. Hence the break condition and the hello commands are not needed, but do no harm. This ‘el-cheapo’ version of the WLoader hardware uses a few resistors and a zener diode as RS interface.

PIC16FA: Introduction, Pin Diagram, Pin Description, Features & Datasheet

Previous post Next post. The remote reset circuit can ddatasheet omitted when the target circuit already has a manual reset eatasheet switchbut it is very convenient to be able to reset the target and hence activate WLoader from the PC.

The 33k reset pull-up and a LED for power indication can be disabled by pulling two pin header jumpers for low-current tests. The current version R Read The current memory location 4 hexadecimal digits is read and coped the content to the communication buffer.

The user must disconnect the RS cable when the application program must run automatically after a reset. R2 is needed when the MAX is a permanent part of the circuit, again to provide the low level on RE2, in this case when no PC is connected.

You may also like: Hence the application loaded by the loader can 16ff87x exactly the same as a stand-alone program downloaded datasueet the 16f WLoader – a 16f application loader. When the target circuit must be kept as simple as possible the real or el-cheapo RS interface, and the remote reset datasgeet can be put in a download dongle.


The use of each functional block inside this controller has already been explained in the previous post. Don’t ask me for help. The L is echoed as? When nothing is connected to the RS connector R1 keeps the 16f input high, which causes the loader to start the application when a reset occurs.

This resistor determines datzsheet level on the line when either the rest of the circuit or the PC is not connected, so in that case the application is started automatically when the PIC is reset. Note the resistor on the single line 116f87x the PIC used for communication.

When the circuit is split between a dongle and the real target R1 must be included in the target so the application will be started on a reset.

The whole gadget can be plugged in where a 16f would fit and adds in-circuit downloading to a circuit. This is the programming method common to all PIC chips. For an overly-clever compiler you can try to let the application start with three NOPs. The Wisp PC command-line tool can be used to download the application datzsheet, to verify the downloading, to start the application program, and provides a simple TTY interface that can be used to communicate with the application.

It is not dataseet for downloading using WLoader.

LVP claims pin B3 as enable pin. WLoader is designed for and tested with the 16f only, but it should be useable with other 16f87x chips when some modifications are made: For program memory the higer two bits are set to 0. Self-programming means that the 16f87x can program its own code FPROM, so – once you have loaded suitable application loader firmware in your target 16f87x – a simple serial interface to your PC is all you need to download and run an application.

Once LVP is disabled in the configuration fuses word this pull-down might no longer be needed, but some people have reported that it is still needed for succesfull HVP programming.


The wisp tool will notice that it communicates with the WLoader firmware, so it sets the default target to 16f The current location is set to the first location of the data memory.

The pseudo RS interface circuit is self-echoing: Your email address will not be published. The protocol adheres to the WBus definition, but the WLoader is always in active mode after datashfet reset of the 16F, so it does not support multiple devices on the same bus. Microchip keeps changing its website, so when these links turn out to be invalid you might have to look around a little.

The right side or the circuit is the same 16F target circuit as used daatasheet the MAX According to the type of the microcontroller, these banks may vary. Note that you must use the correct version because the two version use different polarity of the RS signal.

WLoader – a 16f877 application loader

The loader puts a goto instruction at addresses It does not actually perform the write, but does verify against the stored value, or in case of the configuration fuses word, against a copy of the actual fuses value. For program and configuration memory the higer two bits of a are ignored. The counter is automatically incremented to the next instruction during the current instruction execution. The version number 4 hex digits is copied to the communication buffer. The block diagram shows the taget circuit as far as relevant for WLoader.

Self-programming uses a program executed by the 16f itself. Except for the crystal which must be 20 MHz and the reset see below you can vary this part of the target circuit to suit dstasheet needs, or use what you already have in your design.

This memory is not directly mapped in the register file space.