UART problem 10 Serial Ports

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at last I have time to play with FPGAs .. I wanted to connect arduinos trough serial to the Duo which then talks to the PC. I used the DesignLab example for  "Multiple serial ports " and looked also in


the Duo can talk to itself via the UARTS , but when I connect an Arduino (to uart 1 or change the code ..)there is no communication. I have only one Duo can someone else test ?


Ediit :

int inByte = 4;Serial1.write(inByte);

Serial write works only with a constant , but print does not work at all.







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Hey Jack,


rx,tx  were on the right  pins ... but :


1. in arduino - one can write  "if (Serial.available() >= 2)" , for the  ZPUno the available() function  is only showing if only one byte has arrived. (this is not documented). That is because the Fifo has only signals for full or empty. When I find time I will try to change that.


2. the 5V tolerant pins produced much interference to the data (first I tried them), and some weird error that I had to reset the FPGA by Hand after power up.


3. with pins 22,23 .... I managed the connections, but due to much interference and not a proper shielded  cable I gave up on this Idea.  The problem was I can not trust the data and have to implement some checksum . Maybe the UART is also too sensitive  ? ..



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