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What is the maximum baud rate that the uart of these devices can support?
I'm interested in driving an RS485 link at up to 1 mbps. - Chris |
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Max Baud Rate of LPCxxxx UART?
Started by ●January 9, 2005
Reply by ●January 9, 20052005-01-09
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Hi Chris, From my testing of RS422/485 and a LPC2106 running at 14.7456MHz external clock, 460.8K baud and maybe, just maybe 921.6K. You must also have 120 ohm resistors on the master and the last slave unit as close to the RS422/485 chip as possible. Charles -----Original Message----- From: Chris Graham [mailto:] Sent: Sunday, January 09, 2005 8:40 PM To: Subject: [lpc2000] Max Baud Rate of LPCxxxx UART? What is the maximum baud rate that the uart of these devices can support? I'm interested in driving an RS485 link at up to 1 mbps. - Chris Yahoo! Groups Links |
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Reply by ●January 10, 20052005-01-10
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Hi Chris, don't know the specifics (penalties) of the RS422/485 but the serial interface can go to a maximum of CPU clock divided by 16. So, running at 14.7456 it could go to 921.6 kbaud. Make sure that the divider for the peripherals (VPBDIV) is changed to 1, default after reset is divide by 4. If you go to 1 Mbit, you should have a 16 MHz clock or a multiple thereof. Cheers, Bob --- In , "Charles R. Grenz" <charles.grenz@s...> wrote: > Hi Chris, > > From my testing of RS422/485 and a LPC2106 running at 14.7456MHz > external clock, 460.8K baud and maybe, just maybe 921.6K. > You must also have 120 ohm resistors on the master and the last slave unit > as close to the RS422/485 chip as possible. > > Charles > > -----Original Message----- > From: Chris Graham [mailto:chris_e_gr@y...] > Sent: Sunday, January 09, 2005 8:40 PM > To: > Subject: [lpc2000] Max Baud Rate of LPCxxxx UART? > > What is the maximum baud rate that the uart of these devices can support? > I'm interested in driving an RS485 link at up to 1 mbps. > > - Chris > > > Yahoo! Groups Links |
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Reply by ●January 10, 20052005-01-10
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Is the external clock a clock or a XTAL? (If it's an XTAL you should be able to multiply it up by 4 with the PLL to get a faster peripheral clock (<= 60MHZ) and get 4 times the baud rate). Jane --- lpc2100_fan <> wrote: --------------------------------- Hi Chris, don't know the specifics (penalties) of the RS422/485 but the serial interface can go to a maximum of CPU clock divided by 16. So, running at 14.7456 it could go to 921.6 kbaud. Make sure that the divider for the peripherals (VPBDIV) is changed to 1, default after reset is divide by 4. If you go to 1 Mbit, you should have a 16 MHz clock or a multiple thereof. Cheers, Bob --- In , "Charles R. Grenz" <charles.grenz@s...> wrote: > Hi Chris, > > From my testing of RS422/485 and a LPC2106 running at 14.7456MHz > external clock, 460.8K baud and maybe, just maybe 921.6K. > You must also have 120 ohm resistors on the master and the last slave unit > as close to the RS422/485 chip as possible. > > Charles > > -----Original Message----- > From: Chris Graham [mailto:chris_e_gr@y...] > Sent: Sunday, January 09, 2005 8:40 PM > To: > Subject: [lpc2000] Max Baud Rate of LPCxxxx UART? > > What is the maximum baud rate that the uart of these devices can support? > I'm interested in driving an RS485 link at up to 1 mbps. > > - Chris > > > Yahoo! Groups Links --------------------------------- Yahoo! Groups Links To ___________________________________________________________ ALL-NEW Yahoo! Messenger - all new features - even more fun! http://uk.messenger.yahoo.com |
