How to enable Vybrid TCON Spread Spectrum?

mpfgregory — Tue, 22 Mar 2016 08:18:23 GMT

Our product fails EMI testing because of the display pixel clock. We're using a TFT with TTL interface, controlled by the DCU and TCON drivers. I wonder if it's possible to enable spread spectrum for the TCON module. From the VybridRM I don't understand how the pixel clock is generated. The TCON module has its own Timing Signal Generator (TSG). Is the TSG related to the Clock Controller Module (CCM)? If I enable spread spectrum for PLL1 or PLL2 in the CCM, will this affect the TSG? If not, is there another way to enable spread spectrum for the TCON module?

Thanks for your help

Michael

Re: How to enable Vybrid TCON Spread Spectrum?

mpfgregory — Tue, 22 Mar 2016 14:35:17 GMT

I've found the solution myself. You need to enable spread spectrum for the DCU, not the TCON. In CCM_CSCMR1 you can select PLL1_PFD2 as DCU clock. Then you can enable spread spectrum for PLL1 in ANADIG_PLL1_SS:

clrsetbits_le32(&anadig->pll1_ss, 0xffffffff, (1 << 15) | (4400 << 16) | 11);

topic How to enable Vybrid TCON Spread Spectrum? in Vybrid Processors

How to enable Vybrid TCON Spread Spectrum?

Re: How to enable Vybrid TCON Spread Spectrum?