diff --git a/README.md b/README.md index fa1774d08..3bc988ca8 100644 --- a/README.md +++ b/README.md @@ -399,9 +399,16 @@ If you encounter this, try these things - Make sure to have as short as possible flat-cables connecting your Raspberry Pi with the LED panel. - - Use an adapter board with a bus-driver that acts as level shifter between - 3.3V and 5V. You can find [active adapter PCBs](./adapter/) in a - subdirectory of this project. + - In particular if the chips close to the input of the LED panel + read 74HC245 instead of 74HCT245 or 74AHCT245, then this board will not + work properly with 3.3V inputs coming from the Pi. + Use an [adapter board](./adapter/active-3) with a bus-driver that acts as + level shifter between 3.3V and 5V. + (In any case, it is always a good idea to use the level shifters). + + - A temporary hack to make HC245 inputs work with the 3.3V levels is to + supply only like 4V to the LED panel. But the colors will be off, so not + really useable as long-term solution. - If you can't implement the above things, or still have problems, you can slow down the GPIO writing a bit. This will of course reduce the diff --git a/adapter/active-3/README.md b/adapter/active-3/README.md index bd7f4088a..1950b4bcd 100644 --- a/adapter/active-3/README.md +++ b/adapter/active-3/README.md @@ -8,14 +8,14 @@ Adapter PCB to support up to 3 panels * Open source KiCAD PCB EDA format. * (not very pretty layout, was just lazy and let the auto-router do it). * BOM: - - 4x HCT245 in 20-SOIC (7.5mm package) + - 4x 74HCT245 or 74AHCT245 in 20-SOIC, 7.5mm package. - 4x 100nF ceramic capacitor (0805 package) - 1x 10kOhm resistor (0805 package) - 3x 16pin IDC (=2x8) male receptible to connect the panels. - 1x 40pin female connector to connect to the RPi. * The FAB files are provided as [active3-rpi-hub75-adapter-fab.zip](./active3-rpi-hub75-adapter-fab.zip) -The board is also [shared on OSH Park][osh-active3]. +The board is also [shared on OSH Park][osh-active3] (not affiliated). ![Preview][rendering] ![Real World][real-world] diff --git a/adapter/passive-3/README.md b/adapter/passive-3/README.md index 7a6c7a414..edc08f0b4 100644 --- a/adapter/passive-3/README.md +++ b/adapter/passive-3/README.md @@ -11,7 +11,7 @@ Adapter PCB to support up to 3 panels * (not very pretty layout, was just lazy and let the auto-router do it). * The FAB files are provided as [passive3-rpi-hub75-adapter-fab.zip](./passive3-rpi-hub75-adapter-fab.zip) -This board is [shared on OSH Park][osh-passive3]. +This board is [shared on OSH Park][osh-passive3] (not affiliated). ![Preview][rendering] diff --git a/adapter/passive-rpi1/README.md b/adapter/passive-rpi1/README.md index a249116d0..be79a9b61 100644 --- a/adapter/passive-rpi1/README.md +++ b/adapter/passive-rpi1/README.md @@ -9,7 +9,7 @@ Adapter PCB to connect to Rasbperry Pi1 * (not very pretty layout, was just lazy and let the auto-router do it). * The FAB files are provided as [passive-rpi-hub75-adapter-fab.zip](./passive-rpi-hub75-adapter-fab.zip) -This board is [shared on OSH Park][osh-passive-rpi]. +This board is [shared on OSH Park][osh-passive-rpi] (not affiliated) ![Preview][rendering]