Project board which includes RTC EEPROM

Dear All,
I am planning to design a project board which includes RTC EEPROM Temperature sensor LCD and keypad. RTC and EEPROM are communicating using I2C and LCD connected to PORTD (8bit mode) and keypad also connected to PORTD so my question is if we connect keypad to PORTD and then we press a key how we give priority to keypad to display desired characters
I can not connect keypad to PORTB because RB6 and RB7 use for debugging MY MCU is PIC16f877a
Please advice

PA3040 said:

Dear All,
I am planning to design a project board which includes RTC EEPROM Temperature sensor LCD and keypad. RTC and EEPROM are communicating using I2C and LCD connected to PORTD (8bit mode) and keypad also connected to PORTD so my question is if we connect keypad to PORTD and then we press a key how we give priority to keypad to display desired characters
I can not connect keypad to PORTB because RB6 and RB7 use for debugging MY MCU is PIC16f877a
Please advice

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Hi,

One thing I have learnt about building a dev board, is that you always end up wanting to add something else !
Have you also considered using things like SPI, PWM, Usart /Serial/RS232.

Don't know how you are planning to build it, as one big board ?

What I do find very handy is a row of turned pin ic sockets along side the 40 pin pic socket, this allows you to hook up test devices or connecting wires to a breadboard etc.

Possibly consider a modular approach with standard things like lcd, leds,and switches on the main board and plug in 'project' boards ?
See this link for one simple method -Matrix Multimedia - E-Blocks rapid electronic development kits - Supports PICmicro, AVR, ARM, Altera, CPLD, FPGA devices

Having both the lcd and keypad on PortD will be possible but you need some fancy program code to control both functions.
The software will output the code to the lcd, it does not require any 'refreshing' untill you want to change the data displayed.
Next you will poll the keyboard to see if any key has been pressed, if it has then your keyboard routine takes over.
When you have processed the key data then you output it to the lcd etc.

Assuming you are using a standard HD44780 compatible lcd then you can use it on PortB by using a 6 bit lcd program code instead of the usual 7 bit, so leaving RB6 and 7 clear for the debugger.

If you see the Pk2 User manual it shows how you can share RB6/7 with certain devices while also using them for ICSP, unlike debugger which must have Mclre, Rb6/7 dedicated to it, plus a little bit of user ram.