A simple JDM programmer for PIC microcontrollers - Microcontroller programmers - Microcontroller device circuits. The simplest JDM programmer for PIC on passive components Port and protocol settings when connecting the programmer

One day I decided to assemble a simple LC meter for pic16f628a and naturally it had to be flashed with something. I used to have a computer with a physical COM port, but now I only have USB and a pci-lpt-2com board. To begin with, I assembled a simple JDM programmer, but as it turned out, it did not want to work with either the pci-lpt-com board or the usb-com adapter (low voltage of RS-232 signals). Then I rushed to look for usb pic programmers, but there, as it turned out, everything was limited to the use of expensive pic18f2550/4550, which I naturally didn’t have, and it’s a pity to use such expensive MKs if I very rarely do anything at peaks (I prefer av- Yes, flashing them is not a problem, they are much cheaper, and it seems to me that it is easier to write programs on them). After delving for a long time on the Internet in one of the many articles about the EXTRA-PIC programmer and its various variants, one of the authors wrote that extrapic works with any com ports and even a usb-com adapter.

The circuit of this programmer uses a max232 logic level converter.

I thought that if you use a usb adapter, it would be very stupid to convert the usb to usart TTL, TTL to RS232, RS232 back to TTL levels twice, if you can just take the TTL signals of the RS232 port from the usb-usart converter chip.

So I did. I took the CH340G chip (which has all 8 com port signals) and connected it instead of max232. And this is what happened.

In my circuit there is a jumper jp1, which is not in the extra peak, I installed it because I didn’t know how the TX output would behave at the TTL level, so I made it possible to invert it on the remaining free NAND element and, as it turned out, it was right there is a logical one at the TX pin, and therefore there is 12 volts at the VPP pin when turned on, but nothing will happen during programming (although you can invert TX in software).

After assembling the board, it was time for testing. And here came the main disappointment. The programmer was identified immediately (with the ic-prog program) and started working, but very slowly! In principle - as expected. Then in the com port settings I set the maximum speed (128 kilobaud) and began testing all the found programs for JDM. As a result, PicPgm turned out to be the fastest. My pic16f628a was fully flashed (hex, eeprom and config) plus verification for about 4-6 minutes (reading is slower than writing). IcProg also works, but slower. There were no programming errors. I also tried to flash eeprom 24c08, the result is the same - everything sews, but very slowly.

Conclusions: the programmer is quite simple, it does not contain expensive parts (CH340 - 0.3-0.5 $, k1533la3 can generally be found among radio junk), works on any computer, laptop (and you can even use tablets on Windows 8/10). Cons: it is very slow. It also requires external power for the VPP signal. As a result, it seemed to me that for infrequent flashing of peaks, this is an easy to repeat and inexpensive option for those who do not have an ancient computer with the necessary ports at hand.

Here is a photo of the finished device:

As the song says, “I made him out of what was.” The set of parts is very diverse: both SMD and DIP.

For those who dare to repeat the circuit, almost any one will be suitable as a usb-uart converter (ft232, pl2303, cp2101, etc.), instead of k1533la3, k555 will be suitable, I think even k155 series or a foreign analogue 74als00, it may even work with logical NOT elements of the type k1533ln1. I am attaching my own printed circuit board, but anyone can redraw the wiring there for the elements that were available.

List of radioelements

The proposed programmer is based on a publication from the magazine “Radio” No. 2, 2004, “Programming modern PIC16, PIC12 on PonyProg.” This is my first programmer that I used to flash PIC chips at home. The programmer is a simplified version of the JDM programmer, the original circuit has an RS-232 to TTL converter in the form of a MAX232 microcircuit, it is more universal, but you can’t assemble it “on your knees”. This circuit does not have a single active component at all, does not contain scarce parts and is very simple; it can be assembled without the use of a printed circuit board.

Rice. 1: Schematic diagram of the programmer.

Description of the circuit operation
The programmer circuit is shown in Fig. 1. Resistors in the CLK (clocking), DATA (information), Upp (programming voltage) circuits serve to limit the flow of current. PIC controllers are protected from breakdown by built-in zener diodes, so there is some compatibility between TTL and RS-232 logic. The presented circuit contains diodes VD1, VD2, which “take” the positive voltage from the COM port relative to pin 5 and transfer it to power the controller, thanks to which in some cases it is possible to get rid of an additional power source.

Setting up
In practice, it does not always happen that this programmer will work without adjustment, on the first try, because... The operation of this circuit is highly dependent on the parameters of the COM port. However, for me, on two motherboards Gigabyte 8IPE1000 and WinFast under XP, everything worked right away. If you are too lazy to deal with a broken, more complex programmer circuit, then you should try to assemble this one. Here are some things that may affect:

The newer the mat. board, the developers pay less attention to these ports, because these ports have long become obsolete. You can get rid of this by purchasing a USB-COM adapter, although again the purchased device may not be suitable. The necessary parameters are as follows: the variable voltage must change at least -10V to +10V (log. 0 and 1) relative to the 5th pin of the connector. The supplied current must be at least such that when a 2.7 kOhm resistor is connected between the 5th contact and the contact under test, the voltage does not drop below 10V (I have not seen such boards myself). Also, the port must correctly determine the voltages coming from the controller; at a voltage level close to 0V, but not more than 2V, zero is determined, and accordingly, at a voltage level above 2V, one is determined.

Problems may also arise due to software.
This is especially true for LINUX OS, because... Due to the presence of emulators such as wine, VirtualBox, ports may not work correctly, and a lot of capabilities are required from them. I will touch on these problems in more detail in another article.

Knowing these features, let's start setting it up.
For this, it is very desirable to have the ICProg 1.05D program.
In the program menu, you must first select the appropriate setting in the settings. port (COM1. COM2), select JDM programmer. Then open the “Hardware Check” window, in the “Settings” menu. In this menu, you need to check the boxes one by one and use a voltmeter to measure the voltage at the contacts of the connected connector. If the voltage parameters do not correspond to the norm, then, unfortunately, this may be the cause of inoperability, then you will have to assemble a circuit with an RS-232 TTL converter. Having checked all the boxes, you need to make sure that a supply voltage of about 5V is generated at the zener diode. If the voltages are normal and there are no installation errors, then everything should work. We put the controller in the socket, open the firmware, program it. There is no need to enable checkboxes like “Invert data out” (all are unchecked). Also, do not forget that some batches of controllers may have non-standard parameters, and it is not possible to flash them; in such cases, with this programmer, you can only try to reduce the supply voltage from 5V to 3-4V by connecting accordingly. zener diode, look at the controller for erroneous activation of the LVP (low-voltage programming) mode, how to prevent it, you can read on the Internet for a specific type of controller. It is probably possible to increase the programming voltage of the problematic controller only by complicating the circuit by introducing an amplification stage with a common emitter, powered from an additional power source.

Now let's talk more about the problem with the device's power supply. The programmer was tested with ICProg programs and console picprog under Linux, it should work with any that supports JDM if you connect an additional power source (it is connected through a 1 kOhm resistor to the zener diode, diodes with resistors in this case can be completely excluded). The fact is that the programmer control algorithms for individual software are different, the ICProg program is the most unpretentious. It was noticed that in Windows OS this program raised the required supply voltage on unused pin 2, the same program under the emulator in Linux to another mat. The board was no longer able to do this, but a way out was found by taking power from the programming voltage. In general, I think you can use this programmer with ICProg without additional power. With other software this can hardly be guaranteed, for example, the “native” picprog from the Ubuntu repositories without power simply does not detect the programmer, displaying the message “JDM hardware not found”. It probably either receives some data without applying the programming voltage, or does it too quickly, so that the filter capacitor does not yet have time to charge.

As a basic programmer, we suggest you assemble a JDM compatible programmer, which we called the NTV programmer, using the original design. Below is a diagram of the NTV programmer (using a DB9 socket; not to be confused with a plug).

The programmer assembled according to this scheme repeatedly and accurately flashed controllers (and a number of others) and can be recommended for repetition by novice radio amateurs.

This programmer DOES NOT WORK when connected to laptops, because... The signal levels of the RS-232 interface (COM port) in mobile systems are underestimated. It may also not work on modern PCs where the hardware saves current on the port. So don’t be judgmental, collect and test it on all the computers that come to hand.

Structurally, the programmer board is inserted between the contacts of the DB-9 connector, which are soldered to the contact pads of the printed circuit board. Below is a drawing of the board and a photograph of the assembled programmer.

To complete the information, it should be said that there is another similar programmer that I assembled for microcontrollers in an 8-pin package ( and ). The programmer also works great with these microcontrollers. Below is a drawing of the board and photographs.

Quickly assembling a circuit you like on a microcontroller is not a problem for many radio amateurs. But many people starting to work with microcontrollers are faced with the question of how to program it. One of the simplest programmer options is the JDM programmer.

Programmer ProgCode v 1.0

This program runs on WindowsXP. Allows programming PIC controllers of the middle family (PIC16Fxxx) via the COM port of the computer. The programmer connection indicator (in the upper right corner of the window) turns red if there is no programmer on the port selected in the settings. If the programmer is connected, the program detects it and the indicator in the upper right corner takes the form shown in Figure 1.

SFR File Format

Port and protocol settings when connecting a programmer

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Description of the chip programming process

Let's consider writing information to the flash memory of the microcontroller PIC 16 F 628 A

To transfer 1 bit of information to the microcontroller, you need to set 0 or 1 (depending on the value of the bit) on the data line (DATA) and create a voltage drop (transition from 1 to 0) on the clock line (CLOCK).
One bit for a controller is not enough. He waits for five more in order to perceive this 6-bit message as a command. The controller really likes commands, and they must consist of 6 bits - such is the nature of the PIC 16.
Here is the list and meaning of commands that PIC is able to understand. There are not so many commands - the vocabulary of this controller is small, but don’t think that it is completely stupid - there are devices with fewer commands

"LoadConfiguration" 000000 - Loading configuration

"LoadDataForDataMemory" - 000011 - Loading data into data memory (EEPROM)
"IncrementAddress" 000110 - Increase the address of the PC MK
"ReadDataFromProgramMemory" 000100 - Reading data from program memory
"ReadDataFromDataMemory" 000101 - Reading data from data memory (EEPROM)
"BeginProgrammingOnlyCycle" 011000 - Start programming cycle
"BulkEraseProgramMemory" 001001 - Complete erase of program memory
"BulkEraseDataMemory" 001011 - Complete erase of data memory (EEPROM)

The controller reacts to these commands in different ways. In different ways, after issuing the command, you need to continue the conversation with him.
In order to begin a full-fledged programming process, you must also apply a voltage of 12 volts to the MCLR pin of the controller, and then apply a supply voltage to it. It is in this sequence of voltage supply that there is a certain meaning. After power is applied, if the PIC is configured to operate from the internal RC oscillator, it may begin executing its own program, which is not allowed when programming, as failure is inevitable.
Preliminary supply of 12 volts to the MCLR allows you to avoid such a development.
When writing information to the flash memory of MK programs after the command

"LoadDataForProgramMemory" 000010 - Loading data into program memory

it is necessary to send the data itself to the controller - 16 bits,
which look like this:

“0xxxxxxxxxxxxxx 0.”

The crosses in this word are the data itself, and the zeros at the edges are sent as a frame - this is the standard for PIC 16. There are only 14 significant bits in a word. This series of controllers has a 14-bit command representation format.
After the data word transmission has finished, the PIC waits for the next command.
Since our goal is to write a word into the program memory of the MK, the next command should be the command

"BeginEraseProgrammingCycle" 001000 - Begin a programming cycle

Having received it, the controller disconnects from the outside world for 6 milliseconds, which it needs to complete the recording process.

The signals at the microcontroller pins are generated by a computer using special programs - programmers. COM, LPT or USB ports can be used for signal transmission. Programs such as PonyProg, IsProg, WinPic800 work with the JDM programmer.

JDM programmer circuit

One of the questions when connecting a programmer to a computer is how to ensure selective isolation. To avoid damage to the COM port in the event of a malfunction in the circuit. Some designs use the MAX232 IC, which provides selective isolation and signal level matching. In this scheme, the issue is solved more simply - by using battery power. The signal level coming from the computer is limited by zener diodes VD1, VD2, and VD3. Despite the simplicity of the JDM programmer circuit, it can be used to program most types of PIC microcontrollers.

The assignment of pins for microcontrollers of the PIC16Fxxx series, depending on the type of case, is in most cases standard, but if there is any doubt about this, then it is most reliable to check the datasheet for a specific instance of the MK. Some of the documentation is available on the Russian website http://microchip.ru A complete collection of datasheets and other documentation is located on the website of the PIC microcontroller manufacturer: http://microchip.com

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