Thank you, Xiaofan. I will try to design appropriate trace lengths and impedances in the implementation of the Sigma-Delta. I will use a 4-layer board which should afford some help with the clock transients. Did you use a 4-layer board? I have experienced problems with trace inductance and termination impedances that required a re-layout of the board, even at 12 MHz. So the higher clock frequencies of today are even more challenging. Power supply to the chip should be as low impedance as possible. Let me know how you solve the problem. ----- Original Message ----- From: "Xiaofan Chen" To: "Microcontroller discussion list - Public." Sent: Monday, June 25, 2007 9:23 AM Subject: Re: [EE] anyone worked with PIC24? > On 6/25/07, Rich wrote: >> Thanks for the reply. All information is useful. How much memory did you >> add? I have not worked with SPI before so I want to try it with memory >> and >> a 24-bit A/D. >> > > 24-bit A/D, should be a Sigma-Delta one. Take good care of the SPI > communication because I am having big problems with the SPI communication > to an AD7731 (an 10 year old parts but still a good one for its price). > The > noise in the SPI clock is causing data to jump to the top or freeze in > continuous conversion mode. I am not using a PIC24 though but an > ARM7 MCU from TI. > > Xiaofan > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist