Hello,
I'm seeking from help on trying to set the baudrate dor UART5 on MK60DN512ZVMD10 on my TWR-K60N512. I'm trying to follow this formula, according to the datasheet of the micro-controller:
- UART baud rate = UART module clock / (16 × (SBR[12:0] + BRFD))
I've checked in the same datasheet that the "UART module clock" is sourced by bus clock on micro-controller, and I was thinking of using the default values for bus clock on micro-controller for my board, checking section 5.5.1 Clock divider values after reset of the datasheet:
From my understanding, the micro-controller defaults to a bus clock of "divide by 8", my question is, relative to which clock value?
Is it needed to configure all the registers and components of the MCG and SIM modules to generate a bus clock before attempting to set the UART baudrate, like the following diagram suggests?
I really appreciate your help and share of knowledge and ask for some patience cause i'm really still a beginner trying to get into the world of ARM micro-controllers.
Many thanks in advance. :smileywink:
Ricardo
If you do not configuration the MCG, MCGOUTCLK defauts to about 22.5MHz (32kHz IRC [35156 Hz middle value] * FLL multiplacation of 640).
This means that you will have a system clock of 22.5MHz (typical) and bus clock of the same if you have the LPBOOT configuration set to 1. If you have the LBOOT set to 0 it will be about 2.8MHz for each.
Even if you don't configure the MCG in anyway you can still modifiy the system and bus clocks as you want by simply writing to SIM_CLKDIV1 (doesn't need to wait for anything to lock but make sure that the bus speed is never set higher than the system speed and that the flash clock is not set higher than 25MHz).
UARTs 0 and 1 are clocked from the core clock and the others are clocked from the bus clock.
For UART 5 (bus clock) you can set a baud with the values given in your other thread: Re: I need help with UART5 on TWR-K60N512
Note that with the default clock setting it is neither possible to work with USB nor Ethernet.
Below is a screen shot of the TWR-K60N512 running in the uTasker Kinetis simulator with default LPBOOT = 1 clock setting, showing the speeds involved as well as a Baud of 115200 on UART5 (the 32kHz IRC is assumed to have its typical vaue, which however has some tolerance):
Ricardo
If you do not configuration the MCG, MCGOUTCLK defauts to about 22.5MHz (32kHz IRC [35156 Hz middle value] * FLL multiplacation of 640).
This means that you will have a system clock of 22.5MHz (typical) and bus clock of the same if you have the LPBOOT configuration set to 1. If you have the LBOOT set to 0 it will be about 2.8MHz for each.
Even if you don't configure the MCG in anyway you can still modifiy the system and bus clocks as you want by simply writing to SIM_CLKDIV1 (doesn't need to wait for anything to lock but make sure that the bus speed is never set higher than the system speed and that the flash clock is not set higher than 25MHz).
UARTs 0 and 1 are clocked from the core clock and the others are clocked from the bus clock.
For UART 5 (bus clock) you can set a baud with the values given in your other thread: Re: I need help with UART5 on TWR-K60N512
Note that with the default clock setting it is neither possible to work with USB nor Ethernet.
Below is a screen shot of the TWR-K60N512 running in the uTasker Kinetis simulator with default LPBOOT = 1 clock setting, showing the speeds involved as well as a Baud of 115200 on UART5 (the 32kHz IRC is assumed to have its typical vaue, which however has some tolerance):
The UART5 registers (showing Baud settings in UART_BDH, UART_BDL and UART_C4 are as shown in the simulator's peripheral register display:
Regards
Mark
Kinetis: µTasker Kinetis support
K60: µTasker Kinetis TWR-K60N512 support / µTasker Kinetis TWR-K60D100M support / µTasker Kinetis TWR-K60F120M support
UARTs/PUARTs: http://www.utasker.com/docs/uTasker/uTaskerUART.PDF
For the complete "out-of-the-box" Kinetis experience and faster time to market
