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by mbatte
Fri Mar 16, 2018 12:07 pm
Forum: Compute Module
Topic: CM3/CM3L with BCM2837B0
Replies: 4
Views: 1073

Re: CM3/CM3L with BCM2837B0

A better thermal management is always nice.
by mbatte
Thu Mar 01, 2018 9:31 am
Forum: Compute Module
Topic: EMC problems at 426 MHz with DPI24 enabled
Replies: 9
Views: 1480

Re: EMC problems at 426 MHz with DPI24 enabled

We already tried to disabel all other GPIO except the PCLK with the raspi-gpio tool. This had no effect. We also disabled the PWN in the config.txt with no effect. Another thuogth by our side: for src in arm core h264 isp v3d uart pwm emmc pixel vec hdmi dpi ; do \ echo -e "$src:\t$(vcgencmd measure...
by mbatte
Wed Feb 28, 2018 3:52 pm
Forum: Compute Module
Topic: EMC problems at 426 MHz with DPI24 enabled
Replies: 9
Views: 1480

Re: EMC problems at 426 MHz with DPI24 enabled

Yes, when setting GPIO0 to input with

Code: Select all

raspi-gpio set 0 ip
the peak disappears.

100 Ohm connected to this GPIO at the CMIO3 shows no effect.
by mbatte
Wed Feb 28, 2018 12:18 pm
Forum: Compute Module
Topic: EMC problems at 426 MHz with DPI24 enabled
Replies: 9
Views: 1480

Re: EMC problems at 426 MHz with DPI24 enabled

To your first three points: 1) Our measurements of the power supplies of our base board look stable and quite noise free. Connecting the CM3 to the CM3IO also shows 426 MHz. We assume the power supply of the CM3IO is also okay. Nothing connected to the CM3IO except the CM3. 2) We will check our base...
by mbatte
Wed Feb 28, 2018 8:33 am
Forum: Compute Module
Topic: EMC problems at 426 MHz with DPI24 enabled
Replies: 9
Views: 1480

Re: EMC problems at 426 MHz with DPI24 enabled

Thank you for your fast reply. Yes, correct, we are using a four layer PCB with a complete ground plane. We have set a PCLK of 36.864 MHz (1024 * 600 Pixel @ 60 Hz ) and can measure this frequency with a scope. The emitted frequency can be measured at 426 MHz with a spectrum analyzer. 426 MHz / 36.8...
by mbatte
Tue Feb 27, 2018 6:49 am
Forum: Compute Module
Topic: EMC problems at 426 MHz with DPI24 enabled
Replies: 9
Views: 1480

EMC problems at 426 MHz with DPI24 enabled

Hi everyone! I have some EMC problems using the DPI at the CM3 module. We connected a 7” TFT display (with capacitive touch) to the CM3 via the DPI24. Because the display seems not to use the HSYNC and VSYNC signals, we modified the default DTBS file so we can use the pins for the I2C of the touch m...

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