Richard can you please edit community_ideas micrideksoo oage rhuombustech maintain all of this there revisioons to revisions of email knoen to be not a sustainable way to track detailed important information
On Wednesday, July 18, 2018, Richard Wilbur <richard.wil...@gmail.com> wrote: > Addendum > > Why? > 1. Make VESA DDC lines conform to VESA DDC spec. (VDD=5.0V, I2C > signalling)[1] > 2. Respect VREFTTL in the range of 3.3-5.0V on EOMA side of VESA DDC > lines. > 3. Respect EOMA requirement that all lines except EOMA I2C be tri-stated > at power on. > > How? > 1. Connect pull-up resistors for VESA_SDA(R8) and VESA_SCL(R12) to > VESA_PWR (+5.0V) instead of VREFTTL. Maximum current requirement on > VESA_PWR is ~670uA. > 2. Implement circuit in attached > diagram[EOMA_I2C_circuit_sketch_small.png] on each of SDA and SCL. I have > attached a spreadsheet[EOMA_I2C_VESA_calc.pdf] showing how this > accommodates the I2C signalling for VDD=3.3V=VREFTTL and VDD=5.0V.[2] It > also accommodates the EOMA68 VREFTTL input levels by not allowing the EOMA > side of the signal to exceed one Schottky diode drop(0.3V) above VDD=3.3V. > 3. Enable the current limiting regulator (SY6280) for VESA_PWR (+5.0V on > VGA pin 9) with latch of LCDDE when it first goes active (line coming from > EOMA68 connector). > > References: > > [1] https://en.wikipedia.org/wiki/Display_Data_Channel > [2] http://www.nxp.com/documents/user_manual/UM10204.pdf > _______________________________________________ > arm-netbook mailing list arm-netbook@lists.phcomp.co.uk > http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook > Send large attachments to arm-netb...@files.phcomp.co.uk -- --- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68 _______________________________________________ arm-netbook mailing list arm-netbook@lists.phcomp.co.uk http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook Send large attachments to arm-netb...@files.phcomp.co.uk