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allenhuffman
Joined: 17 Jun 2019
Posts: 552
Location: Des Moines, Iowa, USA
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| PCD set_open_drain_x() |
 Posted: Tue Sep 28, 2021 3:17 pm |
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I found a reference to "set_open_drain_x()" in the General Purpose IO section of the manual, but no details on what x is. I assume it is the port, like other similar calls. Also, header file:
| Code: | _bif void set_open_drain_b(unsigned int16 value);
_bif void set_open_drain_c(unsigned int16 value);
_bif void set_open_drain_d(unsigned int16 value);
_bif void set_open_drain_e(unsigned int16 value);
_bif void set_open_drain_f(unsigned int16 value);
_bif void set_open_drain_g(unsigned int16 value); |
But what is the value? From this article:
https://simple-circuit.com/pic24fj64gb002-lcd-interfacing-ccs-c/
...they write:
| Quote: | For example if I want pin RB0 to be an open-drain output I just write:
set_open_drain_b(1);
For pins RB7, RB8 and RB9 I used:
set_open_drain_b(0x380);
where 0x380 = 896 = 0b0000001110000000 |
It appears the expected value is a bit pattern. The define for PIN_E4 is 1 0111 0001 0100 so that must not be what it is expecting.
Any tips on where I can find some documentation on this?
Thanks, much.
_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 28, 2021 4:21 pm |
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Open the CCS manual pdf file. Make sure the PDF file is opened
at the starting page (the cover). Press Ctrl-F to open up a search
box within the Adobe reader. Type in set_open_drain and press
enter. It will highlight the table of contents entry for:
| Quote: | | set_open_drain_x(value) |
Click on that entry with your mouse.
It will take you to the entry for set_open_drain_x(value) in the text.
That entry tells you what you need to know about the parameter.
CCS manual:
http://www.ccsinfo.com/downloads.php |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Wed Sep 29, 2021 12:45 am |
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and seriously, just use binary. It makes things so much easier.
So for B7, B8 & B9:
set_open_drain_b(0b0000001110000000);
While for E4:
set_open_drain_e(0b0000000000010000);
Much easier to understand what pin is involved.
Understand this only applies on chips that have the ability to set pins to
open_drain mode. |
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allenhuffman
Joined: 17 Jun 2019
Posts: 552
Location: Des Moines, Iowa, USA
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| Posted: Wed Sep 29, 2021 8:22 am |
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| Ttelmah wrote: | and seriously, just use binary. It makes things so much easier.
So for B7, B8 & B9:
set_open_drain_b(0b0000001110000000);
While for E4:
set_open_drain_e(0b0000000000010000);
Much easier to understand what pin is involved.
Understand this only applies on chips that have the ability to set pins to
open_drain mode. |
Looks like another case of "not in the help file."
I noticed the bits, but what are the high bits in the #defines? 5904 for bit four, but what do the 59 bits mean?
_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Wed Sep 29, 2021 9:34 am |
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What #defines?.
I think you are confusing bit numbers with port masks.
The #define for PIN_E4, is the value to be fed to things like the output_high
and output_low functions. Nothing to do with a port mask for things like
this, and TRIS.
Functions that have _a, _b etc. at the end are just talking directly to
the registers associated with the single port. So 'output_b', just talks
to the whole of port B. It expects to receive a byte value to send to the port.
(or int16 for PCD).
The TRIS functions, and this open_drain function, again talk to the registers
for a single port, and expect a byte (or int16 for PCD) value with each
bit corresponding directly to the bit in the port.
This is completely separate from things like output_high, and output_low,
which expect to receive a value that is actually the register address of the
output register (*8 for PCM/PCH, and *16 for PCD), plus the bit number
to operate in this register.
The manual makes this very clear. If you look at the entry for the
open_drain function, it says:
| Quote: |
Parameters:
value – is an 8-bit int with each bit representing a bit of the I/O port.
[PCD] value – is a 16-bit int with each bit representing a bit of the I/O port.
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While if you look as 'output_high', it says:
| Quote: |
Parameters:
The PIN could also be a variable. The variable must have a value equal to one of the constants (like PIN_A1) to work properly. The tristate register is updated unless the FAST_IO mode is set on port A. Note that doing I/O with a variable instead of a constant will take much longer time.
[PCD] pin to write to. Pins are defined in the devices .h file. The actual value is a bit address. For example, port a (byte 0x2C2) bit 3 would have a value of 0x2C2*8+3 or 5651. This is defined as follows: #DEFINE PIN_A3 5651.
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You must not mix the two types of value.
The open_drain function is a port_wide function, not a function that works
or accepts single bit defines. |
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