Maple Hardware Errata and Failure Modes
This page is a collection of known issues and warnings for each revision of
the Maple board. The failure modes aren't design errors, but are easy ways
to break or damage your board permanently. For a list of differences between
the Maple and Arduinos, see the page on compatability.
This batch of boards went on sale in May 2010. They have a darker red
silkscreen and the "infinity-leaf" logo.
Known design errors:
- Resistors on D0, D1: these header pins,
which are RX/TX on USART2 ("Serial2"), have resistors in-line between the
STM32 and the headers. These resistors increase the immpedence of the lines
for ADC reads and affect the open drain GPIO functionality of the pins. These
resistors were accidentally copied over from older Arduino USB designs, where
they appear to protect the USB-Serial converter from TTL voltage on the
headers.
Potential failure modes:
- TTL voltage on non-tolerant pins:
not all header pins are 5v compatible; connecting certain serial devices
in the wrong way could over voltage the pins.
This batch of 100 boards shipped in later 2009. They have a red silkscreen and
the logo is a single pixelated leaf.
Issues:
- ADC noise: generally very high, in
particular when the USB port is being used for communications (including
keep-alive pings when connected to a computer). This issue was resolved in
rev3 with a 4-layer design and a geometricaly isolated ADC Vref plane.
- Resistors on D0, D1: these header pins,
which are RX/TX on USART2 ("Serial2"), have (TODO) Ohm in-line. These
resistors increase the immpedence of the lines for ADC reads and affect the
open drain GPIO functionality of the pins. These resistors were accidentally
copied over from older Arduino USB designs, where they appear to protect the
USB-Serial converter from TTL voltage on the headers.
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