Author: z80avrproject

Side topic … chip labels

Something I had also used to facilitate working with the 8052 SBC project was creating and applying "chip labels" to the DIP packages.  This is not an original thought of mine as I first saw Grant Searle using it on some of his projects.  However, I decided it was best to create a template using … Continue reading Side topic … chip labels

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Software development for the 805x series

While working with my now working 8052 SBC, I spent some time testing with the BASIC-52 (v1.31) program.  One of the things I noticed is that the default value for the XTAL variable is set for 11.0592 MHz.  In looking at the source code, which is written in assembly, I found where the default value … Continue reading Software development for the 805x series

Slow EEPROM reduces maximum oscillator frequency

In my previous post, I had written about having difficulties with the AT89C52's oscillator being unstable and how I cured that issue. Once I had achieved a stable oscillator, I increased the clock to 20 MHz.  All seemed to work properly.  I was able to write a BASIC program and save it to EEPROM using … Continue reading Slow EEPROM reduces maximum oscillator frequency

Oscillator functioning properly – All looks well

In one of my previous posts, I had written that during testing, I found the AT89C52's oscillator to be unstable and unreliable at 11.0592 MHz.  I had also found that the RESET signal going to the AT89C52 via the GAL22V10 was also "lingering" mid-rail before returning low, which was causing intermittent failures to reset the … Continue reading Oscillator functioning properly – All looks well

AT89C52 arrival and more hardware/software testing

The newly purchased AT89C52's from a different vendor arrived in relatively short order.  The original order from a Chinese eBay vendor still have not arrived (as of yet). That seller has issued a refund but from prior attempts to order AT89C52's from what seemed to be different sources, has been met on a few occasions … Continue reading AT89C52 arrival and more hardware/software testing