Home › ELEKTOR FORUMS › Distance Learning Course - Programming Embedded PIC Microcontrollers using Assembly, C and Flowcode › I2c

ELEKTOR FORUMS

Please log in to post a reply or subscribe / unsubscribe to topics

Topic: I2c
Author	Post
HFO48 5 posts Popping In	02-02-2011 04:19 The programs in sections 10.1 and 10.2 compile but there is no display on the LCD.I have copied and used the sample programs provided with the same result.The LCD works when used with other programs and the hardware is connected as in the text. The power to the boards is correct.No jumpers are set on the course board and the LCD is set as jumpers on default. Thanks hfo
GeenBert 81 posts Frequent Visitor	03-02-2011 11:41 Did you power the course board? Is it connected to the correct port? If so TC74 may be malfunctioning. Part K9 on the course board is the TC74. One side of it is metal, is this side facing the course board or is it facing outwards? Another possible cause is interference on the power lines. Keep the plus wires as short as possible and keep them away from cell phones and especially smart phones and see if that helps. Bert
HFO48 5 posts Popping In	04-02-2011 03:53 Power to the course board is correct (+5V).The ports are a and b. The TC74 is metal side out.The plus wires are very short.All electronics have been removed from the work site except the PC and screen. Thanks HFO
GeenBert 81 posts Frequent Visitor	04-02-2011 11:43 A possible cause is that the 18F4455 is not inserted properly into the programmer. Pay particular attention to b0 and b1 (pins 33 and 34). Also double check the configuration settings as described on page 55. Check the brightness control on the LCD to make sure it hasn't accidentally been turned off in between projects. Remove the boards and insert them again to ensure that all pins are making proper contact. Also check that the + wires aren't broken internally (or use a multimeter to check that the course board is indeed powered). If this is all ok then it might be a faulty solder connection on the course board at the TC74, the two resistors or the two capacitors. Or a faulty TC74. In that case it's probably best if you contact Elektor to see how this can be solved. Bert
HFO48 5 posts Popping In	23-02-2011 22:44 Just finished rechecking everthing.I can find no problem with the hardware setup or software(mine or the provided example). Bert before trying to contact Elector ,I just need to know that you are sure that the program works. Thanks Fred
GeenBert 81 posts Frequent Visitor	24-02-2011 10:39 Hi Fred, During the development of the course all programs have been extensively tested, so everything works as described. Just to make sure though I've tried the the C program on page 436 and the Flowcode program from question 10e (as available on the CD that comes with the course) and both work. They show the actual temperature on the LCD and if I pinch the TC74 between my fingers the temperature rapidly rises. There is one last test you yourself might try on the 18f4455. Use the assembly program of page 73 with the described hardware and test if pressing buttons 0 and 1 lights LEDs 0 and 1 (don't try the other buttons). Then swap the LED and button board, and in the assembly program swap port b and c. Now run the program again and repeat the test. If both tests pass then the 18f4455 I2C pins both work as input and output, so the 18f4455 is ok. If either test fails the 18f4455 is faulty. If that test passes the only other cause I can think of is a malfunctioning TC74 (or one of the associated components) on the course board. Contact Elektor to see how this can be solved. Bert