Build your own USB-ASP Programmer CloneBymakeriot2020 FEB 21, 2022 Arduino, ASP programmerUsing more ATMEGA based MCU’s in my recent projects, and not using ready-made Arduino boards for any of them, it became necessary to invest in a dedicated ASP programmer to flash the MCU’s. Huge delays on electronics components, with confirmed orders being mysteriously cancelled due to sourcing issues, and the high cost of “original OEM ASP programmers”, send me on a search for a DIY style programmer, like the old “NOPPP” ( NO PARTS PIC Programmer) in the good old days…Personal computers have changed a lot, and while ATMEGA chips are not PIC’s, I did feel that it could be done. Given the fact that you could also use an Arduino UNO as an ISP, and doing a little more digging, I finally found a very attractive alternative…Thomas Fischl, on his website,https://www.fischl.de/usbasp, has an open-source hardware project, that seemed to be exactly what I needed. His device is capable of programming 5v devices, at various speeds, including a super slow one. He has also written firmware for the device, and although the last update was in 2011, It still seems to be working well, or at least as far as I can see…I did however decide to add my own twist to the design and build in a logic level converter, to be able to program 3.3v devices as well…The modified schematic is below:Schematic Page 1Schematic Page 2I chose to do my own PCB layout, to incorporate the changes listed earlier, namely the logic level conversion from 5v to 3v, as well as adding a 3.3v LDO voltage regulator to provide 3.3v to the target in case it is required.PCB TopsidePCB Bottom Side3D Render of the PCBThe PCB is still in transit from the factory, and thus I will update this article later with pictures of the actual device.Firmware can be flashed using any ASP programmer, Arduino as ISP as well, but with the caveat that you have to use AVRDude from the command line… More on that in the follow-up post… ( I would like to show actual screenshots of the process, and not theory.. ). The links to the firmware are available on https://www.fischl.de/usbasp, courtesy of Thomas Fischl, whom I would like to thank for making this open-source hardware project available freely, as well as for writing and maintaining the firmware.

Today we will look at the remote control unit for the Robotic Toy Car – Part 6.The project is close to being completed, and as such, there are quite a lot of final things that need to be taken care of.One of these will definitely be the final coding, which I will release in the final part of the project, so with that in mind, let us take a look at the remote control unit.Remote Control Unit, designed to be used with ESP-NowI have decided to do something completely different from standard remote control units, being that I will use ESP-Now, a protocol developed by Espressif.ESP-Now runs on the Wifi hardware of the ESP8266 or ESP32 and is basically a peer-to-peer protocol, that does not require Wifi but can co-exist with it on the same device. Outdoors, ESP-Now has a range of about 100m, which should work very well for my intended use.The Remote control, as designed, will have 4 dedicated buttons: forward, reverse, left and right, divided into two groups to make two-handed control easier, similar to a standard game controller. No input on either of the two groups will result in stopping the vehicle, in the case of forwards and backwards, and centring the steering, in the case of the left-right axis.a 3D Rendered Image of the PCB, motion axis on SW1 and SW2, steering axis on SW3 and SW4As I always try to make my designs somewhat reusable for other purposes, I have also broken out most of the unused GPIO pins to header pins, with also adding a jumper on GPIO16 to make deep-sleep wakeup mode possible., You can also re-use the switch pins for other purposes, just remember to first remove the 10k pull-up resistors at R14, R15, R16, and R17…SW4 -> R16 , SW4 = GPIO4SW3 -> R17 , SW3 = GPIO5SW2 -> R15 , SW2 = GPIO13SW1 -> R14 , SW1 = GPIO12GPIO16 can be reused as well, just remove the jumper, but remember that it is pulled up through a LED and a 470ohm resistor…There is no USB-to-serial converter onboard, I have been having quite a lot of headaches with them over the last few months, with almost all CH340G chips that I have purchased, being fake, or dead-on arrivals that don’t work… Sending them back to the suppliers, unfortunately, results in unpleasantries, because even placing them in verified working circuits, still proves them to be not working… This is however not an issue, as it is quite easy to upload the board with an external adapter.The SchematicSchematic Diagram

In this part of the series, Robotic Toy Car – Part 4, We will add some custom side-panels to the project. While the original toy did come with some laser cut aluminum side panels, I decided to replace them with PCB versions, with even more flashing lights (yes, this thing is turning into a “Christmas tree” , but that is what the eventual owner wanted… )These side-panels will not be programmable. They will simply be operated from a standard 555 timer and a couple of other components, to give a flash time of about one second on and off each…It is also an excellent project to showcase the capabilities of PCBWay, in dealing with a “rather difficult” PCB to manufacture. As you may know by now, I use PCBWay‘s services quite extensively, and I also only design my PCB’s with EasyEDA. EasyEDA is however quite limited in some aspects, and as far as myself, making panels of different designs on one PCB with complex shapes is not something that I do every day…Let us take a look at what had to be done, and how well it was manufactured…The PCB LayoutWhat we have here, is basically two mirrored side-panels ( as far as the visible “outside” is concerned anyway ) That consists of 6 led’s per side that will flash alternatively. On the “inside” we have a 555 timer chip, with some resistors and capacitors, as well as transistors that does the switching.The SchematicThe difficulty of this PCB is definitely in the manufacturing. I was however pleasantly surprised with the excellent work that was done by PCBWay. Their Engineering staff did contact me early on in the order, with a suggested plan to manufacture, and once I approved that, they very quickly went on to production. My initial concern was that they suggested “mouse-bites” which we all know can sometimes come out a bit strange…Completed PCB in packaging..I was however extremely pleased when the above parcel arrived… They added side rails, and the “mouse-bytes” were super tiny.After assembly ( not cleaned up yet )After Assembly ( not cleaned up yet )Installed on the toy car bodyThe “almost completed ” Robotic Toy CarWith the completion of the side-panels, it was also time to start work on the power wiring and other essential components of the project, which will get their own detailed post in a few days.the “almost completed” projectSome details on the construction:The toy originally came with a single 500mA 14500 cell, which unfortunately stopped working very soon after only a few uses… This was however one of the reasons why the entire project happened in the first place, so no complaints there.I decided to replace it with a 18560 cell with a capacity of about 1900mA. This cell is much bigger however, and I had to think of where to place it. I decided to put it on the roof, sort of emulating a “spoiler”.Some of the next parts of the project will be the remote control unit, which will basically be an ESP8266 running ESP-Now protocol, as well as a decent battery charging and power distribution circuit, that will protect the Lipo cell from over charging and discharging, as well as provide sufficient power for all the added electronics in the toy car.“But you said it was Robotic, so why have a remote control?”The initial plan for the project did indeed say robotic, but it is also designed to be a learning platform, especially to teach coding. With that in mind, it is definitely better to keep things simple for now, and add sensors and more capabilities later on, especially as I am actually planning to replace the main MCU board with a more powerful ESP32 in a next version anyway.The car body is also extremely cramped, and does not have any space for mounting sensors at all. I plan to remedy that by designing and 3d-printing a whole new custom body shell later… providing that my young friend actually stays interested enough to learn the coding… If he doesn’t, he will as least have a very interesting looking custom remote controlled toy car.

In this, part 3 of the “Giving new Life to an Old Toy Car” series, we will be adding some flashing lights to the toy car project. This will ultimately serve two purposes, with the most obvious being to give some life and excitement to the project ( as the final user will be a young boy of 7, the visual aspect is important). The second purpose is more obscured, and mostly only useable to programmers and coders, or those that will debug the project… The flashing lights will function as status indicators, at startup, as well as during the normal operation of the toy. Obviously, the diagnostic nature should be well obscured so as to not distract from the visual aspects.A short test of the display unit, disguised as a “police-style” flasher unitThe flasher unit is made up of an extremely simple circuit, with only a PCF8574 IO expander, bypass capacitors, some LED lights, and current limiting resistors.The bottom layer of the flasher unit, shows the Io expander, bypass capacitors, and current limiting resistors.The top layer is designed to be as clean as possible, with only LEDs and some labelingSchematicSchematicThe schematic is straightforward, with no surprises, consisting only of a few components, like the PCB8574, bypass capacitors, current limiting resistors, and of course the LEDs. It is also important to remember that I plan to use this entire robot car to teach a young boy to program microprocessors. I believe that visual is best, thus, all the lights ??CodingAs this is still a project in quite a lot of development stages, I will not publish my exact code at this moment. You can however look forward to the future conclusion post, which will contain all my code at that stage.For now, however, we need to keep in mind that the PCF8574 is an I2C port expander, with an 8-bit IO port.It is thus possible to do something simple like the below:#include <Wire.h>void setup() {wire.begin();wire.beginTransmission(0x20);wire.write(0b11111111); // All LEDS off// our circuit is sinking current into the io expanderwire.endTransmission();delay(1000); // delay for illustration purposes, production code will use// non blocking codewire.beginTransmission(0x20);wire.write(0b10100101); // All blue LED on// our circuit is sinking current into the io expanderwire.endTransmission();delay(1000);}void loop() {}Obviously, this is just a very quick example and is meant to just test functionality. Your own application will ultimately determine the exact code that you would need.