From: Dan Nelson [mailto:Dan.Nelson@romteck.com]
Sent: Monday, 28 May 2012 12:15 PM
To: General mailing list for gumstix users.; Keane, Ben (STRX)
Subject: RE: [Gumstix-users] ADC characteristics
Sounds like your voltage follower doesn’t have enough grunt to drive the ADC. Where are you measuring the 0.8 volts? At the input to the buffer or at its output?
From: Keane, Ben (STRX) [mailto:email@example.com]
Sent: Tuesday, May 22, 2012 2:31 PM
To: General mailing list for gumstix users.
Subject: [Gumstix-users] ADC characteristics
Hello Mailing List,
I am wondering if anyone has characterized the ADC's on the gumstix? I am experiencing a non-linear response... depending on the buffers (on a custom board) output resistance, the characteristic changes. It seems that until the ADC value reaches 0.8V with a measured current draw of 0.24mA the ADC will just measure 0... After that point, it will start to measure linearly. When driven directly from the power supply the voltage response is linear, but when diven from an voltage follower, it is not.
Any help would be much appreciated.
PROPRIETARY: This e-mail contains proprietary information some or all of which may be legally privileged. It is intended for the recipient only. If an addressing or transmission error has misdirected this e-mail, please notify the authority by replying to this e-mail. If you are not the intended recipient you must not use, disclose, distribute, copy, print, or rely on this e-mail.
CAUTION: This message was sent via the Public Internet and its authenticity cannot be guaranteed.