https://paz00.ru/index.php?action=history&feed=atom&title=Usbasp_spi 2026-06-16T18:58:09Z История изменений этой страницы в вики MediaWiki 1.39.10 https://paz00.ru/index.php?title=Usbasp_spi&diff=970&oldid=prev 2016-01-18T07:07:32Z

<p>Новая страница: «===Intro=== USBASP [http://www.fischl.de/usbasp/] is a Atmega8/Atmega48 based USB to ISP programmer. It can be picked up from Aliexpress for about $1.5 [http://ru…»</p> <p><b>Новая страница</b></p><div>===Intro===<br /> USBASP [http://www.fischl.de/usbasp/] is a Atmega8/Atmega48 based USB to ISP programmer. It can be picked up from Aliexpress for about $1.5 [http://ru.aliexpress.com/af/usbasp.html].<br /> <br /> It is possible to use the USBASP (firmware update is likely needed) to interact with SPI devices.<br /> <br /> I implemented a library for the USBASP using libusb. I used the new library with the raspberry pi 2 based software for communication with my device.<br /> <br /> <br /> ===USBASP===<br /> libusb can be used to control USBASP stick. USB bulk transfer is used. All commands supported by the USBASP can be found in the USBASP firmware sources.<br /> <br /> USBASP have TRANSMIT command. This command sends 4 bytes of data on SPI bus. Also USBASP pushes SS pin low (active) during <br /> initialization and keeps it in this state before disconnect.<br /> <br /> <br /> ===MFRC522===<br /> I have a device based on MFRC522 chip that can be connected to an SPI bus. <br /> Protocol is simple: 2 bytes command to read ow write registers. Description can be found in the datasheet (it is free and easy to find).<br /> <br /> I failed to get it working with my device as is and I had to modify firmware. Modification is simiple. I added a new command (I called it TRANSMIT2) to transmit data in the format MFRC522 understands. The command controls SS pin and sends only two bytes of data.<br /> <br /> '''After update I lost ability to program Atmega chips for some reason. Initial firmware had no ability to set SPI clock, while updated firmware has. Maybe this is a reason. I didn't figure it out.'''<br /> <br /> <br /> I implemented usbasp library. This library have interface that compatible with the bcm2835 library (library for SPI communication on the raspberry pi 2).<br /> Then I took rpi-rc522 software (based on bcm2835 library) and modified it to utilize my usbasp library.<br /> <br /> <br /> ===Links===<br /> TODO: add links to the software.</div>

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