Please give us your advice on the below customer inquiry;
We are using TL16C754C QUAD UART, if we do continous data transfer, not able to recive the data from the device(chip). the LSR bit0 not getting high, some times we read 0xFF on data bus. we are not using interrupt pins.
What are the baud rates of the two nodes? Are they different?
What is the word length? 8N1?
What crystal or oscillator is used on each node
Are you using FIFO mode or non-FIFO mode?
Can you send code showing how you initialize and set up the TL16C754C device?
1. Our baud rate is 9600 for TX and RX, its 8N1 only2.1.8432MHz crystal we are using, tested FIFO & non FIFO modes alsoThe problem is: After the initialization the communication getting started, after some time the data is not receiving in the FIFO. the LSR  is always 0. the same problem appearing in all the UART channels. we have tried in non FIFO mode also. Tested on External loop back mode UART A : Tx <-> UART A :Rx UART B : Tx -> UART C: Rx UART C: Tx -> UART B: RxInitialization sequence (A2 A1 A0) = (Value)QUAD_UART_LCR (3) = 0x80 -->DLL_DLH_ENABLE;QUAD_UART_DLL (0) = 0x0C --> 0x000CQUAD_UART_DLH (1) = 0x00QUAD_UART_LCR (3) = 0x00 --> ENABLE_PRIMARY_REGQUAD_UART_LCR (3) = 0x03 --> 8N1QUAD_UART_IIR_FCR (2) = 0x00 --> Disable FIFOQUAD_UART_IER (1) = 0x00 --> DISABLE_ALL_INTERRUPTHere with I have attached the initialization for the QUAD UART for your reference.
Any updates on the customer inquiry.
Please ask the customer to return the failing devices for Failure Analysis (FA). Our lab bench test (TL16C754CPM (PM package)) does not show this failure.
What is the date code on the top of the failing devices?
Is the RXRDY# signal monitored to indicate when a character is received?
I don't see any problems with the initialization code but it might be useful to reset the FIFOs to a known state and clear the FIFO pointer, even though DMA mode 0 is used (see red text below)
Initialization sequence (A2 A1 A0) = (Value)QUAD_UART_LCR (3) = 0x80 -->DLL_DLH_ENABLE;QUAD_UART_DLL (0) = 0x0C --> 0x000CQUAD_UART_DLH (1) = 0x00QUAD_UART_LCR (3) = 0x00 --> ENABLE_PRIMARY_REGQUAD_UART_LCR (3) = 0x03 --> 8N1QUAD_UART_LCR (2) = 0x04 --> RESET TX and RX FIFOsQUAD_UART_IIR_FCR (2) = 0x00 --> Disable FIFO and select DMA Mode 0QUAD_UART_IER (1) = 0x00 --> DISABLE_ALL_INTERRUPT
Can the customer provide a oscilloscope trace of the data bus and TX and RX lines from a Tek MSO4104 or a LeCroy scope?
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