Dave Miller

MC9S08AW16 SCI Noise Flag

Discussion created by Dave Miller on Oct 18, 2007
Latest reply on Oct 18, 2007 by Dave Miller
Hello All,
OK I have already generated an SR # 1-393967504 yesterday afternoon but no response yet from Freescale.  This is more of an issue that others may have seen before so hopefuly posting here might generate a couple of response to help out.
I seem to be getting the Noise Error Flag set on specific Bytes of data sent. Here is some details:

Codewarrior 6.0
MC9S08W16 Micro
Using the AsyncroSerial bean
Settings: 9600, 8, N, 1
VCC = 5V
I am sending a simple string "CP01\n\r" to the serial port on the Micro. I have tried from both Hyperterminal & from my Master Microcontroller and I consistently get a Noise Flag on the 'P' or the '0'.

I have attached a screen shot of a 'P' being sent to the RXD pin on the AW16. This exact signal created a Noise Error but it looks clean to me.
I have also done some further investigation. Using Hyperterminal I sent 30 each, every letter in the alphabet (Upper & Lower) plus 0..9. I found ONLY the following characters caused the Noise flag to be set:
0 - 0x30
8 - 0x38
P - 0x50
X - 0x58
a - 0x61
p - 0x70
q - 0x71
x - 0x78
y - 0x79
Every other alpha character wes recieved without any errors.
Any ideas on what is causing the Noise Error Flag to be set?