HP 39gs and SD card

[matthiaspaul]

(10-29-2017 03:34 PM)rcpdvc Wrote:  R67 sw #WP - GND 100k 104 WriteEnable. Not required with newrpl or bootloader.

I haven't tried myself, does newRPL ignore the write protection switch? Doesn't sound like the best of ideas to me then...

Quote:C74 5.CLK - GND <10p -

I have omitted C74 at all. What the purpose of increasing CLK line capacitance? Noise filtering? Anyway it should be small enough to fit specification limits for total line capacitance (<40pF).

Yes, it is good practise to add some 10pF to the clock of SD cards. This reduces the emission of higher frequencies (harmonics) to avoid EMI problems. Otherwise you might "hear" your calculator in nearby radios.

Greetings,

Matthias