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How to Safely Use SPI + DMA with W5100S Without CS Timing Errors?

When using SPI + DMA with the WIZnet W5100S, deasserting CS too early can corrupt transactions even if DMA transfer-complete interrupts fire.

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Published January 15, 2026

117 UCC

8 WCC

23 VAR

Original author: zilong032 · ChinaOriginal source (new tab)

How to Safely Use SPI + DMA with W5100S Without CS Timing Errors?

Project description

How to Safely Use SPI + DMA with W5100S Without CS Timing Errors? (W5100S에서 SPI + DMA 사용 시 CS 타이밍 문제를 안전하게 해결하는 방법은?) Summary (40–60 words) When using SPI + DMA with the WIZnet W5100S, deasserting CS too early can corrupt transactions even if DMA transfer-complete interrupts fire. This article explains why DMA TC is insufficient, illustrates the correct SPI timing model, and presents a WIZnet-recommended, beginner-safe method to manage CS reliably for industrial-grade Ethernet communication. 1. Background: Why New Users Hit This Problem The W5100S is a hardware TCP/IP Ethernet controller…

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