![]() We need to set both UART devices with the same baud rate to have the proper transmission of data. Baud Rateīaud rate is the number of bits per second (bps) a UART device can transmit/receive. These UART settings are the baud rate, data length, parity bit, number of stop bits, and flow control. UART has settings that need to be the same on both devices to have proper communication. Bits can change because of the transmission distance, magnetic radiation, and mismatch baud rates, among other things. Data loss in transmission happens when a bit changed its state while being transmitted. The receiving UART device uses the parity bit to determine if there was a data loss during transmission. After rebuilding the byte, it is stored in the UART buffer. It may need to receive several packets before it can rebuild the whole data byte from the data frames. If there are no errors in transmission, it will then proceed to strip the start bit, stop bits, and parity bit to get the data frame. The receiving UART device checks the received packet (via RX pin) for errors by calculating the number of 1’s and comparing it with the value of the parity bit contained in the packet. That post may give you some ideas.After preparing the packet, the UART circuit then sends it out via the TX pin. I was trying to get some idea about how to reduce noise, so I posted it back then and had a discussion with fellow forum members. When noise is low (and power is good), things run well. ![]() I swapped devices (I have a "real" Arduino, and a home made), swapped I2C clock, and swapped I2C LCD. With 8MHz wave on, I would hit errors in minutes. When noise is high (32MHz square wave on, square wave line running close to I2C lines), I would hit error error within a minute or two. With the two tests that took hours and hours to finish, the average was 3 errors in 11 million. When noise was very low (no square wave), I was able to do 11 million read-after-write with 3 errors (total) - I encounter my error after 10million, so 11 million became the bar for the second run. The noise I was trying to reduce was when the DS1307 has squarewave turned on. My test was to write than read back the 56 bytes of nvram on the DS1307. I have 3 I2C devices (not including the MCU) and found the I2C rather works reliable when noise is low. I was trying to minimize noise impact on my devices. I did some extensive tests back around Christmas time after making a DS1307 clock. I am wondering if you have devices not being happy at 3.3V. I found that if I loaded the board down and pull the power below about 4.8V, my LCD and other devices go nuts frequently. First, the 3.3V - I am using 5V and I have a couple of LCD 20x4. I think the 3.3V and/or noise may be an issue. You're doing serial out to what's presumably 5v without level shifting Still not clear there but if that's the case you could be injecting 5v into your 3.3v circuit which would be bad. Code: atmega328bbA.name=ATmega328 breadboard (8 MHz internal clock)(via ArduinoISP) =stk500 _size=30720 =arduino:arduinoisp =57600 _fuses=0圎2 _fuses=0xDA # BOD on #_fuses=0x05 # BOD OFF _fuses=0x07 =arduino:atmega =ATmegaBOOT_168_atmega328_pro_8MHz.hex _bits=0x3F _bits=0x0F =atmega328p _cpu=8000000L =arduino:arduino It's also a good idea to put a bit of a delay into your setup procedure like 5 seconds to give everything a chance to start up fully but not until you've sorted out your clock speeds.
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