{"id":938,"date":"2013-02-12T02:54:29","date_gmt":"2013-02-12T01:54:29","guid":{"rendered":"http:\/\/www.sciencetronics.com\/greenphotons\/?p=938"},"modified":"2025-06-16T18:38:15","modified_gmt":"2025-06-16T16:38:15","slug":"hacking-an-avr-programmer","status":"publish","type":"post","link":"https:\/\/www.sciencetronics.com\/greenphotons\/?p=938","title":{"rendered":"Hacking an AVR programmer"},"content":{"rendered":"

(see also my recent appendix to this topic: Hacking an AVR programmer II – especially if you have an ATmega88-based programmer!<\/a>)<\/strong><\/p>\n

On eBay I recently purchased a set of cute small USB AVR programmers which I intend to use in the course 1TE663 Microcontroller Programming at Uppsala University<\/a>.
\n

\"\"<\/a>
MK-USBISP-V3.00 programmer in an aluminum shell on eBay.<\/figcaption><\/figure>
\nAfter waiting for one month for the delivery from China the package finally arrived today. Unlike other programmers which I purchased before, these come with a sturdy aluminum shell and in happy colors.<\/p>\n

However, connecting the first programmer to my PC brought me quickly back to earth – it was not recognized as an USBasp. OK, it would not be the first delivery from China with broken or counterfeit electronics, so I tested the second one…<\/p>\n

At that time I got a bit confused, because the programmer registered as an HID unit on the USB with vid=0x03EB & pid=0xc8b4. Not as an USBasp with vid=0x16c0 & pid=0x05dc.<\/p>\n

This is the point where I usually ask Google. So I did and I found some threads discussing the same issue and pointing out, that these programmers needed a different software and were not at all compatible with avrdude. BAD!<\/p>\n

But of course, one should be able to reprogram the programmer using another programmer. At my home this is not a henn and egg problem, since I have accumulated several AVR programmers. <\/p>\n

Ok, I downloaded the USBasp firmware from Thomas Fischl<\/a>, flashed the programmer after inserting the self-programming jumper:
\n

\"\"<\/a>
Self-programming jumper on the MK-USBISP-V3.00 AVR programmer.<\/figcaption><\/figure><\/p>\n

Since the original firmware is protected by the lock-bit fuses, I had to fully erase the chip first, then set the fuses correctly to HFUSE=0xc9 LFUSE=0xef and then flash the .hex file. I tried first the 2009-firmware from Thomas Fischl and the first observation was that instead of the red LED which was on previously, now the programmer showed a blue light.<\/p>\n

But: Windows would not at all recognize this device as any USB device. Nothing showed up. I got confused. I tried both WinXP and Win7 – to no avail. Well, perhaps this programmer was not hardware compatible to the USBasp? Let’s have a look…
\n

\"\"<\/a>
AVR programmer MK-USBISP-V3.00: component side.<\/figcaption><\/figure>
\n
\"\"<\/a>
AVR programmer MK-USBISP-V3.00: solder side.<\/figcaption><\/figure><\/p>\n

There are some tiny, yet important, differences to the original USBasp programmer: in the USBasp USB-D- is connected to pin PB0, USB-D+ to PB1 and PD2\/INT0. Here also USB-D- was connected to a pin on port D: PD3\/INT1. Well, this should not really make a difference, and I continued my search for differences. OK, for some reason, also the LEDs are connected in parallel to 2 port pins each – so what…<\/p>\n

In despair I decided to look into the source code of the USBasp firmware. The header files: OK – pin assignments were as expected, nothing special here. But let’s wait, where is the definition of the utilization of port D? Well, it was in the main.c file:<\/p>\n

int main(void) {
\n  uchar i, j;
\n
\n  \/* no pullups on USB and ISP pins *\/
\n  PORTD = 0;
\n  PORTB = 0;
\n  \/* all outputs except PD2 = INT0 *\/
\n  DDRD = ~(1 << 2);<\/div><\/div>\n

hey – wait a second? All pins of port D are defined as output, except for PD2\/INT0? I always tell my students to only define pins as output, which are really used as output… And what happens here? <\/p>\n

Since the modified design also connected USB-D- to PD3\/INT1, the rather aggressive definition of output pins leads to a unsolvable conflict, when suddenly PD2 is driving against the USB signals from the host!<\/p>\n

Changing this little piece of code solved the problem. Rather conservative I set all pins of port D as input (none of them is currently used as output!):<\/p>\n

int main(void) {
\n  uchar i, j;
\n
\n  \/* no pullups on USB and ISP pins *\/
\n  PORTD = 0;
\n  PORTB = 0;
\n  \/* all PDx input *\/
\n  \/* MK-USBISP v3.0 *\/
\n  DDRD = 0x00;<\/div><\/div>\n

I compiled the code, flashed it onto the AVR programmer using another AVR programmer
\n…and behold: it works!<\/p>\n

I will contact Thomas Fischl and tell him about this observation – perhaps the modification will be implemented in the distributed firmware on his homepage.<\/p>\n

Here is a .zip-archive of the modified firmware. The .hex file for use with an ATmega8 is found in the default<\/em> subdirectory.
\nDownload ZIP archive: 20130212_mega8_usbisp<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

(see also my recent appendix to this topic: Hacking an AVR programmer II – especially if you have an ATmega88-based programmer!) On eBay I recently purchased a set of cute small USB AVR programmers which I intend to use in the course 1TE663 Microcontroller Programming at Uppsala University. After waiting for one month for the […]<\/p>\n","protected":false},"author":1,"featured_media":943,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"enabled":false},"version":2}},"categories":[46,22,11,8],"tags":[],"class_list":["post-938","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-avr","category-computers_en","category-electronics_en","category-everything_en","entry","has-media"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.sciencetronics.com\/greenphotons\/wp-content\/uploads\/2013\/02\/USB-ISP-Programmer.jpg","jetpack_shortlink":"https:\/\/wp.me\/p48grL-f8","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/posts\/938","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=938"}],"version-history":[{"count":17,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/posts\/938\/revisions"}],"predecessor-version":[{"id":2477,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/posts\/938\/revisions\/2477"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=\/wp\/v2\/media\/943"}],"wp:attachment":[{"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=938"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=938"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sciencetronics.com\/greenphotons\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=938"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}