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LPC 2148 ISP programming problem

mystery iit

Hi everyone

I am new to programming LPC 2148.I am trying to program the micro controller using UART0.
I am using flash magic to program the micro.

I have connected the following pins to a FTDI chip:

19-RX input of FTDI
21-TX output of FTDI
23-VCC 3.3V
25-GND
41-GND through a push button switch(will be set to ground when pressed
57-GND through a push button switch for reset.

apart from this,i connected pin 61 and 62 to crystal coupled with 22pF capacitors.
I have set a baudrate of 9600 and checked if the com port matches.

I have got an error saying Failed to autobaud -step 1.

I have two LPC break out boards.
One of them has a crystal on the board .So i have not connected the crystal(pins 61 and 62).With all the other pins remaining the same,the LPC 2148 is programmed. The crystal on the board is not connected to pin 61 and 62,it shows it is connected to pins 3 and 5 through a resistor of 600 ohms

But if try the same circuit and add a 12 mhz crystal to pin 61 and 62 i get the error.Is there anything i need to change in the cirsuit? Thanks in advance.

  • 0

    => Failed to autobaud

    Maybe you also need some other pins like RTS/CTS.

  • 0 in reply to John Linq

    First of all,thanks for the reply.

    You have mentioned that I have to connect RTS and CTS.But I am using UART0 to program and it does not have RTS and CTS.

    I havent connected it to the other breakout board which has an onboard crystal and it programs.

    I think it either has to do with the fact that I have connected the crystal wrong or that the micro controller does not work.

    So can anyone please confirm the pin connections for the crystal?

    Also do i need to connect a 32 KHz signal to the MCU?

    Thank You

  • 0

    Thank you for the reply.

    I need to have a custom designed board for the project .Which is why i would like to use my own programmer which would be a part of the board.

    I have just noticed that there are two differences

    1)I was supposed to connect 18 pf capacitor to the 12 MHz crystal.I connected 22pf ,I thought it wouldnt make a difference.

    2) I havent connected the 32.768 KHz capacitor.

    I will see if any one of this is the issue.

    Thanks for the reply again.

  • 0 in reply to mystery iit

    You may use your custom board, but you can definitely used the development board schematics for designing your board.
    Hope you are trying to design a PCB rather than working on a board with loose wires running from one-end-to-other, as in case if any problem occurs, troubleshooting will be very difficult and time consuming.

  • 0 in reply to Ash J

    I have got the LPC 2148 programmed by using my circuit.For others facing this issue

    The issue was,I had to connect the vcc (PIN 51)to 3.3 v.It wasnt getting 3.3 and
    once i connected it,it started working.

    So the pin connections are as mentioned in the first post with the following additions:

    1)32.768 KHz crystal on pin 3 and 5.
    2)3.3 on vbat (pin 49) and VCC(Pin 51)

    Hope this helps.