I have the following problem using the M41T94 with my setup using a PIC18F8720. I have connected the SPI pins of the Real time clock to the HW SPI pins of the PIC. Also for the Chip Enable(/E) Pin of the RTC I used the A4 pin of the PIC. The setup of SPI is done using the following line:
setup_spi(SPI_MASTER|SPI_L_TO_H|SPI_CLK_DIV_16);
I am trying to hold the A4 pin that is connected to Chip Enable high all the time as instructed by the datasheet yet the command output_high(PIN_A4)does not pull the pin high as I am seeing on the Oscilloscope.
Is there anything about the A4 pin that is peculiar that I should know about? Is my SPI setup correct?
Thanks
Neutone
Joined: 08 Sep 2003 Posts: 839 Location: Houston
Posted: Thu Feb 26, 2004 3:31 pm
Is that the pin with pull down only?
altanb Guest
Posted: Thu Feb 26, 2004 4:28 pm
the datasheet says the following on that pin. I did not realize that before:
Quote:
Input/output or external clock input for Timer0.
Output is open-drain type.
Buffer: Schmitt Trigger input
Is there still a way to use this pin for my purpose?
Neutone
Joined: 08 Sep 2003 Posts: 839 Location: Houston
Posted: Thu Feb 26, 2004 7:22 pm
Tie a pull up resistor from that pin to the voltage supply. You will be able to use it as if it were any other output.
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