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Adrian Cable
Joined: 12 Aug 2004
Posts: 1
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| Undocumented compiler features: RTOS, RS232 software UART |
 Posted: Thu Oct 14, 2004 3:14 pm |
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Hello,
It's come to my attention that the CCS compiler (at least my version, 3.190) supports a large number of undocumented functions and options. Some are pretty useful, e.g. there's some cool stuff with #use rs232. For example, many times it's been asked how to define a software UART on the same pins as the hardware UART. Many kludges have been proposed, but the easiest way is just to use the undocumented force_sw flag:
#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7,force_sw)
Multi-master mode for I2C:
#use i2c(multi_master,sda=XXX,scl=XXX,force_hw)
Plus, there is #use rtos(rtos_run=XXX, rtos_yield=XXX, rtos_terminate=XXX) and a corresponding #task - I haven't been able to figure out how to use these.
Does anyone have any further info on these features?
-A |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Oct 14, 2004 5:14 pm |
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The RS232 and I2C stuff is in the help file:
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#USE RS232
Syntax:
#use rs232 (options)
Elements:
Options are separated by commas and may be:
STREAM=id
Associates a stream identifier with this RS232 port. The identifier may then be used in functions like fputc.
BAUD=x
Set baud rate to x
XMIT=pin
Set transmit pin
RCV=pin
Set receive pin
FORCE_SW
Will generate software serial I/O routines even when the UART pins are specified.
BRGH1OK
Allow bad baud rates on chips that have baud rate problems.
DEBUGGER
Indicates this stream is used to send/receive data though a CCS ICD unit. The default pin used in B3, use XMIT= and RCV= to change the pin used. Both should be the same pin.
RESTART_WDT
Will cause GETC() to clear the WDT as it waits for a character.
INVERT
Invert the polarity of the serial pins (normally not needed when level converter, such as the MAX232). May not be used with the internal UART.
PARITY=X
Where x is N, E, or O.
BITS =X
Where x is 5-9 (5-7 may not be used with the SCI).
FLOAT_HIGH
The line is not driven high. This is used for open collector outputs. Bit 6 in RS232_ERRORS is set if the pin is not high at the end of the bit time.
ERRORS
Used to cause the compiler to keep receive errors in the variable RS232_ERRORS and to reset errors when they occur.
SAMPLE_EARLY
A getc() normally samples data in the middle of a bit time. This option causes the sample to be at the start of a bit time. May not be used with the UART.
RETURN=pin
For FLOAT_HIGH and MULTI_MASTER this is the pin used to read the signal back. The default for FLOAT_HIGH is the XMIT pin and for MULTI_MASTER the RCV pin.
MULTI_MASTER
Uses the RETURN pin to determine if another master on the bus is transmitting at the same time. If a collision is detected bit 6 is set in RS232_ERRORS and all future PUTC's are ignored until bit 6 is cleared. The signal is checked at the start and end of a bit time. May not be used with the UART.
LONG_DATA
Makes getc() return an int16 and putc accept an int16. This is for 9 bit data formats.
DISABLE_INTS
Will cause interrupts to be disabled when the routines get or put a character. This prevents character distortion for software implemented I/O and prevents interaction between I/O in interrupt handlers and the main program when using the UART.
Purpose:
This directive tells the compiler the baud rate and pins used for serial I/O. This directive takes effect until another RS232 directive is encountered. The #USE DELAY directive must appear before this directive can be used. This directive enables use of built-in functions such as GETC, PUTC, and PRINTF.
When using parts with built-in SCI and the SCI pins are specified, the SCI will be used. If a baud rate cannot be achieved within 3% of the desired value using the current clock rate, an error will be generated. The definition of the RS232_ERRORS is as follows:
No UART:
· Bit 7 is 9th bit for 9 bit data mode (get and put).
· Bit 6 set to one indicates a put failed in float high mode.
With a UART:
· Used only by get:
· Copy of RCSTA register except:
· Bit 0 is used to indicate a parity error.
Examples:
#use rs232(baud=9600, xmit=PIN_A2,rcv=PIN_A3)
Example Files:
ex_sqw.c
Also See:
getc(), putc(), printf()
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| Quote: |
#USE I2C
Syntax:
#use i2c (options)
Elements:
Options are separated by commas and may be:
MASTER
Set the master mode
SLAVE
Set the slave mode
SCL=pin
Specifies the SCL pin (pin is a bit address)
SDA=pin
Specifies the SDA pin
ADDRESS=nn
Specifies the slave mode address
FAST
Use the fast I2C specification
SLOW
Use the slow I2C specification
RESTART_WDT
Restart the WDT while waiting in I2C_READ
FORCE_HW
Use hardware I2C functions.
NOFLOAT_HIGH
Does not allow signals to float high, signals are driven from low to high
SMBUS
Bus used is not I2C bus, but very similar
Purpose:
The I2C library contains functions to implement an I2C bus. The #USE I2C remains in effect for the I2C_START, I2C_STOP, I2C_READ, I2C_WRITE and I2C_POLL functions until another USE I2C is encountered. Software functions are generated unless the FORCE_HW is specified. The SLAVE mode should only be used with the built-in SSP.
Examples:
#use I2C(master, sda=PIN_B0, scl=PIN_B1)
#use I2C(slave,sda=PIN_C4,scl=PIN_C3
address=0xa0,FORCE_HW)
Example Files:
ex_extee.c with 2464.c
Also See:
i2c_read(), i2c_write()
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Thu Oct 14, 2004 5:33 pm |
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Strange...my help file does not mention any of these:
| Quote: |
FORCE_SW
Will generate software serial I/O routines even when the UART pins are specified.
SAMPLE_EARLY
A getc() normally samples data in the middle of a bit time. This option causes the sample to be at the start of a bit time. May not be used with the UART.
RETURN=pin
For FLOAT_HIGH and MULTI_MASTER this is the pin used to read the signal back. The default for FLOAT_HIGH is the XMIT pin and for MULTI_MASTER the RCV pin.
MULTI_MASTER
Uses the RETURN pin to determine if another master on the bus is transmitting at the same time. If a collision is detected bit 6 is set in RS232_ERRORS and all future PUTC's are ignored until bit 6 is cleared. The signal is checked at the start and end of a bit time. May not be used with the UART.
LONG_DATA
Makes getc() return an int16 and putc accept an int16. This is for 9 bit data formats.
DISABLE_INTS
Will cause interrupts to be disabled when the routines get or put a character. This prevents character distortion for software implemented I/O and prevents interaction between I/O in interrupt handlers and the main program when using the UART.
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Readme.txt doesn't mention FORCE_SW (but it explains the rest). I wasn't aware this features existed.
It seems the have finally updated their help file. I am using PCWH 3.190, IDE version 3.46.
| Quote: |
Plus, there is #use rtos(rtos_run=XXX, rtos_yield=XXX, rtos_terminate=XXX) and a corresponding #task - I haven't been able to figure out how to use these.
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This is still in beta:
http://www.ccsinfo.com/news.shtml |
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