Programming an LPCXpresso LPC1769 via the UART

[cfbsoftware]

It is very easy to program an Embedded Artists LPC1343 LPCXpresso board / baseboard combination with Astrobe using the USB / UART0 connection on the baseboard. Unfortunately the same is not true for the LPC1769 LPCXpresso due to restrictions imposed by the baseboard's compatibility with ARM's 'mbed' development board.

To solve this problem I have made a simple adapter board from Veroboard that allows UART0 of a LPC1769 LPCXpresso to be connected to a USB / FTDI dongle e.g.

http://www.coridiumcorp.com/catalog/pro ... ucts_id=83

(NOTE: Similar adaptors are available elsewhere at half the price. However, they usually have CTS input accessible rather than the DSR output. Having a DSR output available means that Astrobe can automatically set the MCU into bootloader mode which makes programming the devices so much more convenient)

The adapter board also provides easy access via jumper wires to the LPC1769 pins for +3.3v, GND, SSP0 / 1 (for SPI devices) and I2C1 communication. The photo shows it connected to the SparkFun HMC 6352 Compass Module:

http://www.sparkfun.com/products/7915

compass.jpg

This combination was used to develop the LPC1769 / I2C Compass source code example which can be downloaded from this forum:

viewtopic.php?f=9&t=199

The following photo shows the adaptor board without the LPC1769 board mounted.

veroboard.jpg

A similar adaptor board could be used for programming an LPCxpresso LPC1343 via UART0 and experimenting with SPI / I2C breakout boards without having to use a baseboard.

[cfbsoftware]

Similar adaptors are available elsewhere at half the price. However, they usually have CTS input accessible rather than the DSR output. Having a DSR output available means that Astrobe can automatically set the MCU into bootloader mode which makes programming the devices so much more convenient)

I've now found a suitable FTDI Basic Breakout board (DEV-09873) at Sparkfun which gives you access to both the RTS and DSR outputs for $US14.95.

[pcayuela]

Could you put the connections detail in this LPC1769 board for UART0 please? Thank you in advance.

[pcayuela]

One more question: what would be the procedure of firmware uploading in case of using a USB-UART converter that have CTS/RTS but no DSR/DTR? We only have that kind by now. Hope to get a more complete one soon.

[cfbsoftware]

The UART0 connections details for the LPCXpresso LPC1769 board and the SparkFun FTDI Basic Breakout (DEV-09873) are:

Code: Select all

FTDI        LPC1769

DTR         J6-4    Reset
RX          J6-21   P0.2  (UART0 TX)
TX          J6-22   P0.3  (UART0 RX)
3.3V        J6-2    VIN
CTS         J6-51   P2.10 (Bootloader)
GND         J6-1    GND

To put the LPC1769 into bootloader mode, press the reset button, ground pin P2.10 and then release the reset button. This is detailed in section 32.3 of the NXP LPC176x/5x User manual:

The flash boot loader code is executed every time the part is powered on or reset. The loader can execute the ISP command handler or the user application code. A LOW level after reset at pin P2.10 is considered an external hardware request to start the ISP command handler. Assuming that power supply pins are on their nominal levels when the rising edge on RESET pin is generated, it may take up to 3 ms before P2.10 is sampled and the decision on whether to continue with user code or ISP handler is made.

It is SO much more convenient when you have DTR and CTS connected ...

[pcayuela]

I really appreciate your quick help.
In our University laboratory have no budget and works on donations, from both professors and students sometimes; moreover here in Argentina we have great problems with imported materials because of restrictions and devaluations of local currency, but soon hope to get USB-UARTs with better signaling than those we get from Galileo kit donation from Intel.
Thank you again.