AT89S5253 SPI Problem

Question

Hello, I am using an Atmel AT89S8253 MCU with the W5100 controller via SPI. Although software (bit-banging) SPI does work, I cannot use the integrated hardware SPI of the 89S8253. I’ve tried all modes, but even mode 0 does not work, reducing the ISP-Speed didn’t work either. On the other hand, I can drive SD-Cards and a 128x160 TFT-Display at full speed (12Mhz SPI-clock) without any problems in the same circuit. Has anyone else got similar problems? Regards, Roland

Seppel · Answer

Hi, I own a 20 MHz 2-channel analog scope, but don’t think that I can make good enough pictures of the waves. What signals would you like to see? Sck vs. Mosi and CS vs. Sck? Before I used hardeware SPI inside the 89S8253 with SD-Card, display and w5100, I used only software SPI with an Atmel 89S82 and dicovered that I had to adjust my SPI routine specially for the w5100. Although all components claim to expect mode 0. And I programmed mode 0 for SD and display before I tried the w5100. Since software SPI is quite slow it can’t be a real timing problem. It is more a problem when each signal has to be asserted in general. (IMHO) Hat do you think about it ? Can I contact Wiznet about this somehow? Cheers, Roland

Seppel · Answer

Hi, I use an Arduino Ethernet-Shield that has an inverter for /CS → SEN. So the reqs of that AN should be met. It’s a pity the shield also uses a resistor network for adjusting voltage to 3.3V, but I have alread checked the voltage levels and waves, which seemed all right to me. But I am going to check it again… I used the 00 01 02 03 - scheme writing to the w5100 for debugging of the soft-SPI-routine. Thanks, Roland

Seppel · Answer

Hi again, it took me some time , but now I know what went wrong. I did not reset the W5100 correctly. Strange, it works via software SPI then but gets the hiccups when I use Hardware SPI. Thank you for your help!