UART functioning - Forums Re: UART functioning No idea why I'm never able to attach docs.Drop me an email at kmmankad at gmail for the code.

Wed, 16 Nov 2011 07:22:12 -0600
Re: UART functioning Priyanka,

A couple of things:

1.Please upgrade to the latest version(1.0 SP2 as of today) available.(You can collect it from me,rather than downloading it)

2.I have thrown together some code,for basic UART Rx with an Interrupt Routine to handle that data,do go through it.This code works with no issues.

Possible pitfalls that youre stuck in:

-Disable Address mode : Set that to None.(we're not doing 485)

-Clearing Interrupt : Use a call to UART_ReadRxStatus(); to clear the interrupt


Anyway,check out the attached code.


Wed, 16 Nov 2011 07:20:28 -0600
Re: UART functioning PRIYANKA,


1) Can you please tell us more about the configuration of UART you are using?

2) What is the Rx Buffer size you are using? If the Rx Buffer size is more than 4, then "Rx On Byte Receive" is enabled on default and Interrupt will occur upon receiving a byte.

Enable the Global Interrupt  by uncommenting the CyGlobalIntEnable in the main code so that the ISR will be executed.

3) Powering of both the device has to be taken care of. Make sure that the Receiver PSoC is initialized before the transmitter PSoC starts transmitting.


Wed, 16 Nov 2011 00:22:19 -0600
Re: UART functioning one more prob... i tried communicatin two psoc kits thru UART i/f... one is transmittin and the other is receivin.. but in receiver PSOC lcd , its nt reading the character sent by TX but rather displayin upside dwn U ... is this sm prob in setting again..???

Tue, 15 Nov 2011 23:49:34 -0600
Re: UART functioning thnks a lot dasq... it wrkd.. :)

Tue, 15 Nov 2011 22:58:12 -0600
Re: UART functioning Nice to hear that. 

Tue, 15 Nov 2011 16:51:26 -0600
Re: UART functioning I happened to be on-site and the problem is now rectified.(it was a drive mode issue)

Tue, 15 Nov 2011 05:47:30 -0600
Re: UART functioning  Try not to connect to any thing, just with the Psoc board, and sent something like 0xAA via the uart in a loop. See if you can get any waveform from the UART output pin first.

Tue, 15 Nov 2011 04:40:38 -0600
Re: UART functioning Hi PRIYANKA,


A project was created for Interfacing PSoC 3/5 with GSM Modem. It can be found in the following forum topic:


What I understand from your statement is that you are using DB9 connector present on PSoC3 kit and the DB9 connector present on the GSM Modem for this interface.

For a PC, the DB9 connector (male) has the following pinout:

Pin 2 = Receiver

Pin 3 = Transmitter

Pin 5 = Ground.


But other development boards (including PSoC development kit and GSM Modem) will have the Rx and Tx pins in reverse order, that is, Pin 2 = Transmitter and Pin 3 = Receiver.

So, if you want to interface GSM with PSoC development board, you'll ned to connect Tx and Rx in criss-cross fashion. You can get UART cable which has this configuration or build one using a 2+1 cable and inverting the connection (Rx --> Tx and Tx --> Rx).

Tue, 15 Nov 2011 03:32:21 -0600
Re: UART functioning hi.. we r not using any voltage converter(MAX232). We r directly connecting RS232 PSOC to RS232 of GSM module..


Tue, 15 Nov 2011 03:00:12 -0600
Re: UART functioning PRIYANKA,


Here are some of the questions which will help you narrow down on the error:

1) Assuming that you are using CY8CKIT-001 kit, are you using the port pins directly (TTL Logic) or using the RS232 voltage level (utilizing the on-board MAX232 and DB9) for communication? If you are using RS232, then the jumper J10 (RS232_PWR) present close to the DB9 connector should be closed.

2) Are the pins set to the right drive modes? The Tx Pin should be a Digital Output pin with a "Strong Drive" mode. Rx Pin should be a Digital Input pin with "High Impedance Digital" mode.

Tue, 15 Nov 2011 01:41:56 -0600
Re: UART functioning Hi PRIYANKA,


Are you using UART in Full Duplex or Half Duplex mode?

1) You need to connect the Tx of PSoC to Rx of Arduino and Rx of PSoC to Tx of Arduino.

2) The ground pin (Pin 5 of DB9 connector) should be connected to the ground of Arduino board.

3) Make sure that the baud rate of both the transceivers are the same (eg 9600, 19200, etc).

4) You can get started by experimenting with the UART example project shipped along with PSoC Creator. In the Component Catalog right-click on the UART Component and select "Find Example Project". You can modify the example project according to your requirement for interfacing with Arduino.

Tue, 15 Nov 2011 01:30:01 -0600
Re: UART functioning also with DSO i checked whthr TX is trannsmitting anythning..but i cnt c ny waveform displayed on DSO that mean the pin i m programmin as transmitter is not configured as TX whr all should i make the changes..?

Tue, 15 Nov 2011 01:27:14 -0600