100 ohms is a good starting point. Important to place it close to the transmitter.
If using a 4+ layer PCB that has an unbroken ground plane directly underneath the traces and especially with wider traces, you might want a somewhat lower...
The series resistor is placed between the IC pin that drives the signal voltage, and the rest of the signal trace.
(If we put the series resistor on the other side, near the input pin, we get reflections and other nasty stuff, because electrical...
Maybe you've already considered signal quality issues, but if not, look for other recent threads where series resistors have been recommended. I recall one about a week ago where 5 SPI chips on the same with a Teensy 4.1 and an "expansion...
Thanks for the detailed answer and ideas! The SN74HC157 seems like a great solution. Also, I didn't think of routing the clock signal the same way as I did with the data signal, which makes total sense as you point out. The MOSI+MISO1+MISO2+CLK...
I do suspect the issues alexandros is seeing are due to timing mismatch between clock and data signals, as well as noise. Schmitt triggers on input can help with the noise, but to fix the timing issues, both clock and data signals must be routed...
Here's a PDF to the schematic of the bus board. This schematic doesn't include the Teensy, as this is located in another board that connects to this bus board. Anyway, it is a rather complex system, and I don't know if sharing all of it would...
I'm using the 74HC595 shift register, and the clock and latch pins are shared among all chips, and not daisy chained. What you said about sync might be the culprit. I'm trying out different versions with a modified shiftOut() function, where I...
For pure shift registers:
Let's assume we use three signals: SCLK, MOSI, and MISO.
Each socket receives SCLK_PREV, MOSI_PREV, and MISO_PREV from the previous socket, forwarding them to the next socket as SCLK_NEXT, MOSI_NEXT, MISO_NEXT. (That...
Instead of a tree-like structure, where the signals pass through several transistors, you should consider a bus like structure.
I prefer to use unidirectional voltage level translators like TI TXU0304 for SPI, TXU0204 for UART with hardware...
I'm trying to build a modular system where modules that contain shift registers can connect to a bus board. To avoid hard-coding the number and positions of these modules on the bus board (there are sixteen sockets where modules can connect...
Even if it's working, 2 things you might consider to improve signal quality are series resistors and placement of the GND plane or traces.
Adding 50 to 220 ohm resistors in series (ideally near the transmitting side) can really help. See the...