Conv TTL Blocking issueshttps://ohwr.org/project/conv-ttl-blo/issues2019-02-12T09:59:21Zhttps://ohwr.org/project/conv-ttl-blo/issues/1Unnecessary pull-up resisors on flash chip2019-02-12T09:59:21ZDenia Bouhired-FerragUnnecessary pull-up resisors on flash chipAt the bottom of sheet 7, there are some pull-up resistors on the W\_n
and Hold\_n input pins of the flash memory. These (R195 and R230) are
unnecessary and those pins can be tied to Vcc P3V3
directly.
![](/uploads/07f9b214b534ef912052619ee57dca73/1507275917174-0.png)
Note that, if this (obsolete) flash chip is replaced, as per issue
\#1655, this work package can be ignored and closed.
### Files
* [1507275917174-0.png](/uploads/07f9b214b534ef912052619ee57dca73/1507275917174-0.png)https://ohwr.org/project/conv-ttl-blo/issues/4LED lines need pull-down resistors2019-02-12T09:59:22ZDenia Bouhired-FerragLED lines need pull-down resistorsLED lines from FPGA are negative logic and are connected to front and
rear panel LEDs through inverting schmidt triggers.
These LEDs are supposed to light up immediately at board power up, hence
why the negative logic is used. It was assumed that these lines will be
Low during FPGA configuration.
However, user I/O pins of the FPGA are set to be **floating** during
power up.
Moreover, the data sheet of the inverting schmidt triggers does not
recommend using floating inputs.
Although the correct behaviour is observed on prototypes, the use of
floating inputs on the schmidt triger may happen to be problematic in
noisy environments,
If a new version of this board is to be produced, pull-down resistors
are recommended at the input of the schmidt trigger inverters.