m2mb_uart.h File Reference

UART library implementation. More...

Go to the source code of this file.

Data Structures
struct	M2MB_UART_CFG_T
	UART ioctl configuration. More...

Macros
#define	NULL   0

Typedefs
typedef void(*	m2mb_uart_ind_callback) (INT32 fd, M2MB_UART_IND_E uart_event, UINT16 resp_size, void *resp_struct, void *userdata)
	Transmit and receive operation callback type. More...

Enumerations
enum	M2MB_UART_IOCTL_REQUEST {   M2MB_UART_IOCTL_SET_CFG = 0, M2MB_UART_IOCTL_GET_CFG, M2MB_UART_IOCTL_SET_BR, M2MB_UART_IOCTL_GET_BR,   M2MB_UART_IOCTL_SET_FCTL, M2MB_UART_IOCTL_GET_FCTL, M2MB_UART_IOCTL_SET_PARITY_MODE, M2MB_UART_IOCTL_GET_PARITY_MODE,   M2MB_UART_IOCTL_SET_STOP_BITS, M2MB_UART_IOCTL_GET_STOP_BITS, M2MB_UART_IOCTL_SET_BITS_PER_CHAR, M2MB_UART_IOCTL_GET_BITS_PER_CHAR,   M2MB_UART_IOCTL_SET_TX_TIMEOUT = 14, M2MB_UART_IOCTL_GET_TX_TIMEOUT, M2MB_UART_IOCTL_SET_RX_TIMEOUT, M2MB_UART_IOCTL_GET_RX_TIMEOUT,   M2MB_UART_IOCTL_SET_CB_FN, M2MB_UART_IOCTL_GET_CB_FN, M2MB_UART_IOCTL_SET_CB_USERDATA, M2MB_UART_IOCTL_GET_CB_USERDATA,   M2MB_UART_IOCTL_SET_POWER_STATE, M2MB_UART_IOCTL_GET_POWER_STATE, M2MB_UART_IOCTL_GET_OP_MODE, M2MB_UART_IOCTL_GET_RTS_STATE,   M2MB_UART_IOCTL_GET_DTR_STATE, M2MB_UART_IOCTL_SET_CTS, M2MB_UART_IOCTL_SET_DSR, M2MB_UART_IOCTL_SET_DCD,   M2MB_UART_IOCTL_SET_RING, M2MB_UART_IOCTL_NOF_REQ }
	UART configuration requests. More...
enum	M2MB_UART_FCTL_E { M2MB_UART_FCTL_OFF = 0, M2MB_UART_CTSRFR_AUTO_FCTL, M2MB_UART_FCTL_MAX }
	UART flow control type. More...
enum	M2MB_UART_PARITY_E {   M2MB_UART_NO_PARITY = 0, M2MB_UART_ODD_PARITY, M2MB_UART_EVEN_PARITY, M2MB_UART_SPACE_PARITY,   M2MB_UART_PARITY_MAX }
	UART parity mode. More...
enum	M2MB_UART_STOP_BITS_E {   M2MB_UART_0_5_STOP_BITS = 0, M2MB_UART_1_0_STOP_BITS, M2MB_UART_1_5_STOP_BITS, M2MB_UART_2_0_STOP_BITS,   M2MB_UART_STOP_BITS_MAX }
	UART number of stop bits. More...
enum	M2MB_UART_BITS_PER_CHAR_E {   M2MB_UART_5_BITS_PER_CHAR = 0, M2MB_UART_6_BITS_PER_CHAR, M2MB_UART_7_BITS_PER_CHAR, M2MB_UART_8_BITS_PER_CHAR,   M2MB_UART_BITS_PER_CHAR_MAX }
	UART number of bits per character. More...
enum	M2MB_UART_IND_E { M2MB_UART_TX_EV, M2MB_UART_RX_EV, M2MB_UART_DTR_EV }
	UART event type. More...
enum	M2MB_UART_PIN_VALUE_E { M2MB_UART_LOW_VALUE, M2MB_UART_HIGH_VALUE }
	UART pin voltage value. More...

Functions
INT32	m2mb_uart_open (const CHAR *path, INT32 flags,...)
	m2mb_uart_open opens a UART device. More...
INT32	m2mb_uart_close (INT32 fd)
	m2mb_uart_close closes a UART device. More...
INT32	m2mb_uart_ioctl (INT32 fd, INT32 request,...)
	m2mb_uart_ioctl configures an open UART device. More...
SSIZE_T	m2mb_uart_read (INT32 fd, void *buf, SIZE_T nbyte)
	m2mb_uart_read reads data from an open UART device. More...
SSIZE_T	m2mb_uart_write (INT32 fd, const void *buf, SIZE_T nbyte)
	m2mb_uart_write writes data to an open UART device. More...

Detailed Description

UART library implementation.

m2m/m2m_generic/common/m2mb_inc/m2mb_uart.h

The following functions are implemented:

• m2mb_uart_open()
• m2mb_uart_close()
• m2mb_uart_ioctl()
• m2mb_uart_read()
• m2mb_uart_write()

Note

Dependencies: m2m/m2m_generic/common/m2mb_inc/m2mb_types.h

Author

Morgan Deidda

Date

04/01/2018

Typedef Documentation

m2mb_uart_ind_callback

typedef void( * m2mb_uart_ind_callback) (INT32 fd, M2MB_UART_IND_E uart_event, UINT16 resp_size, void *resp_struct, void *userdata)

Transmit and receive operation callback type.

This type defines the callback functions that the client can set in the UART open configuration or get by m2mb_uart_ioctl API.

Enumeration Type Documentation

M2MB_UART_BITS_PER_CHAR_E

enum M2MB_UART_BITS_PER_CHAR_E

UART number of bits per character.

This type defines the number of bits per character that the client can set in the UART open configuration or get by m2mb_uart_ioctl API.

Enumerator
M2MB_UART_5_BITS_PER_CHAR	5 bits per character
M2MB_UART_6_BITS_PER_CHAR	6 bits per character
M2MB_UART_7_BITS_PER_CHAR	7 bits per character
M2MB_UART_8_BITS_PER_CHAR	8 bits per character

M2MB_UART_FCTL_E

enum M2MB_UART_FCTL_E

UART flow control type.

This type defines the flow control type that the client can set in the UART open configuration or set/get by m2mb_uart_ioctl API.

Enumerator
M2MB_UART_FCTL_OFF	Disable flow control
M2MB_UART_CTSRFR_AUTO_FCTL	Use CTS/RFR flow control with auto RX RFR signal generation

M2MB_UART_IND_E

enum M2MB_UART_IND_E

UART event type.

This type defines the indications which can be passed to the callback.

Enumerator
M2MB_UART_TX_EV	Transmitted data Event
M2MB_UART_RX_EV	Received data Event
M2MB_UART_DTR_EV	Received RTS Event

M2MB_UART_IOCTL_REQUEST

enum M2MB_UART_IOCTL_REQUEST

UART configuration requests.

This enum defines the requests wich can be passed to the function m2mb_uart_ioctl()

Enumerator
M2MB_UART_IOCTL_SET_CFG	set whole uart device configuration
M2MB_UART_IOCTL_GET_CFG	get whole uart device configuration
M2MB_UART_IOCTL_SET_BR	set uart baudrate
M2MB_UART_IOCTL_GET_BR	get uart baudrate
M2MB_UART_IOCTL_SET_FCTL	set uart flow control type
M2MB_UART_IOCTL_GET_FCTL	get uart flow control type
M2MB_UART_IOCTL_SET_PARITY_MODE	set uart parity mode
M2MB_UART_IOCTL_GET_PARITY_MODE	get uart parity mode
M2MB_UART_IOCTL_SET_STOP_BITS	set uart number of stop bits
M2MB_UART_IOCTL_GET_STOP_BITS	get uart number of stop bits
M2MB_UART_IOCTL_SET_BITS_PER_CHAR	set uart number of bits per character
M2MB_UART_IOCTL_GET_BITS_PER_CHAR	get uart number of bits per character
M2MB_UART_IOCTL_SET_TX_TIMEOUT	set synchronous write timeout in ms (if 0, waits indefinitely until the write is completed)
M2MB_UART_IOCTL_GET_TX_TIMEOUT	get synchronous write timeout in ms (if 0, waits indefinitely until the write is completed)
M2MB_UART_IOCTL_SET_RX_TIMEOUT	set synchronous read timeout in ms (if 0, waits indefinitely until the read is completed)
M2MB_UART_IOCTL_GET_RX_TIMEOUT	get synchronous read timeout in ms (if 0, waits indefinitely until the read is completed)
M2MB_UART_IOCTL_SET_CB_FN	set callback function pointer (if NULL, action is synchronous)
M2MB_UART_IOCTL_GET_CB_FN	get callback function pointer (if NULL, action is synchronous)
M2MB_UART_IOCTL_SET_CB_USERDATA	set callback data pointer
M2MB_UART_IOCTL_GET_CB_USERDATA	get callback data pointer
M2MB_UART_IOCTL_SET_POWER_STATE	set current power state
M2MB_UART_IOCTL_GET_POWER_STATE	get current power state
M2MB_UART_IOCTL_GET_OP_MODE	get current operational mode of device (see +CFUN)
M2MB_UART_IOCTL_GET_RTS_STATE	get current RTS state
M2MB_UART_IOCTL_GET_DTR_STATE	get current DTR state
M2MB_UART_IOCTL_SET_CTS	set CTS pin
M2MB_UART_IOCTL_SET_DSR	set DSR pin
M2MB_UART_IOCTL_SET_DCD	set DCD pin
M2MB_UART_IOCTL_SET_RING	set RING pin

M2MB_UART_PARITY_E

enum M2MB_UART_PARITY_E

UART parity mode.

This type defines the parity mode that the client can set in the UART open configuration or get by m2mb_uart_ioctl API.

Enumerator
M2MB_UART_NO_PARITY	no parity
M2MB_UART_ODD_PARITY	odd parity
M2MB_UART_EVEN_PARITY	even parity
M2MB_UART_SPACE_PARITY	space parity

M2MB_UART_PIN_VALUE_E

enum M2MB_UART_PIN_VALUE_E

UART pin voltage value.

This type defines the pin output voltage that the client can set by m2mb_uart_ioctl API.

Enumerator
M2MB_UART_LOW_VALUE	Set pin output LOW.
M2MB_UART_HIGH_VALUE	Set pin output HIGH

M2MB_UART_STOP_BITS_E

enum M2MB_UART_STOP_BITS_E

UART number of stop bits.

This type defines the number of stop bits that the client can set in the UART open configuration or get by m2mb_uart_ioctl API.

Enumerator
M2MB_UART_0_5_STOP_BITS	0.5 stop bits
M2MB_UART_1_0_STOP_BITS	1.0 stop bits
M2MB_UART_1_5_STOP_BITS	1.5 stop bits
M2MB_UART_2_0_STOP_BITS	2.0 stop bits

Function Documentation

m2mb_uart_close()

INT32 m2mb_uart_close

(

INT32

fd

)

m2mb_uart_close closes a UART device.

m2mb_uart_close closes a UART device freeing the data associated to the file descriptor passed as parameter.

Parameters

[in]

fd

File Descriptor returned by m2mb_uart_open()

Returns

returns 0 on SUCCESS, -1 on FAILURE.

Note

m2mb_uart_close(fd);

int main()
{
  INT32 fd;
  INT32 retVal;
  fd = m2mb_uart_open("/dev/tty1", 0);
 
  //... use UART device ...
 
  retVal = m2mb_uart_close(fd);
  if ( retVal != -1 )
    printf( "m2mb_uart_close succeeded");
}

m2mb_uart_ioctl()

INT32 m2mb_uart_ioctl	(	INT32	fd,
		INT32	request,
			...
	)

m2mb_uart_ioctl configures an open UART device.

m2mb_uart_ioctl sets/gets the full UART configuration or single settings by means of requests listed in enum M2MB_UART_IOCTL_REQUEST.

Parameters

[in]	fd	first parameter is the File Descriptor returned by m2mb_uart_open()
[in]	request	second parameter indicates the action to be performed. The allowed values ??are those listed in enum M2MB_UART_IOCTL_REQUEST.
[in,out]	cfg	third parameter can be a pointer to a previously defined variable or a value, depending on the action requested by the second parameter (see following note for further details).

Returns

returns 0 on SUCCESS, -1 on FAILURE.

Note

Use cases:

• Action: M2MB_UART_IOCTL_SET_CFG

  Description: set whole uart device configuration

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pCfgStruct(M2MB_UART_CFG_T *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_CFG, &cfgStruct)

• Action: M2MB_UART_IOCTL_GET_CFG

  Description: get whole uart device configuration

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pCfgStruct(M2MB_UART_CFG_T *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_CFG, &cfgStruct)

• Action: M2MB_UART_IOCTL_SET_BR

  Description: set uart baudrate

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), baudRate(UINT32)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_BR, 115200)

• Action: M2MB_UART_IOCTL_GET_BR

  Description: get uart baudrate

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pBaudRate(UINT32 *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_BR, &baudRate)

• Action: M2MB_UART_IOCTL_SET_FCTL

  Description: set uart flow control type

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), flowControl(M2MB_UART_FCTL_E)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_FCTL, M2MB_UART_CTSRFR_AUTO_FCTL)

• Action: M2MB_UART_IOCTL_GET_FCTL

  Description: get uart flow control type

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pFlowControl(M2MB_UART_FCTL_E *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_FCTL, &flowControl)

• Action: M2MB_UART_IOCTL_SET_PARITY_MODE

  Description: set uart parity mode

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), parityMode(M2MB_UART_PARITY_E)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_PARITY_MODE, M2MB_UART_NO_PARITY)

• Action: M2MB_UART_IOCTL_GET_PARITY_MODE

  Description: get uart parity mode

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pParityMode(M2MB_UART_PARITY_E *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_PARITY_MODE, &parityMode)

• Action: M2MB_UART_IOCTL_SET_STOP_BITS

  Description: set uart number of stop bits

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), stopBits(M2MB_UART_STOP_BITS_E)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_STOP_BITS, M2MB_UART_1_0_STOP_BITS)

• Action: M2MB_UART_IOCTL_GET_STOP_BITS

  Description: get uart number of stop bits

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pStopBits(M2MB_UART_STOP_BITS_E *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_STOP_BITS, &stopBits)

• Action: M2MB_UART_IOCTL_SET_BITS_PER_CHAR

  Description: set uart number of bits per character

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), bitsPerChar(M2MB_UART_BITS_PER_CHAR_E)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_BITS_PER_CHAR, M2MB_UART_8_BITS_PER_CHAR)

• Action: M2MB_UART_IOCTL_GET_BITS_PER_CHAR

  Description: get uart number of bits per character

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pBitsPerChar(M2MB_UART_BITS_PER_CHAR_E *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_BITS_PER_CHAR, &bitsPerChar)

• Action: M2MB_UART_IOCTL_SET_TX_TIMEOUT

  Description: set synchronous write timeout in ms (if 0, waits indefinitely until the write is completed)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), timeout(UINT16)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_TX_TIMEOUT, 100)

• Action: M2MB_UART_IOCTL_GET_TX_TIMEOUT

  Description: get synchronous write timeout in ms (if 0, waits indefinitely until the write is completed)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pTimeout(UINT16 *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_TX_TIMEOUT, &timeout)

• Action: M2MB_UART_IOCTL_SET_RX_TIMEOUT

  Description: set synchronous read timeout in ms (if 0, waits indefinitely until the read is completed)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), timeout(UINT16)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_RX_TIMEOUT, 100)

• Action: M2MB_UART_IOCTL_GET_RX_TIMEOUT

  Description: get synchronous read timeout in ms (if 0, waits indefinitely until the read is completed)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pTimeout(UINT16 *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_RX_TIMEOUT, &timeout)

• Action: M2MB_UART_IOCTL_SET_CB_FN

  Description: set callback function pointer (if NULL, action is synchronous)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), cb_fn(m2mb_uart_ind_callback)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_CB_FN, cb_fn)

• Action: M2MB_UART_IOCTL_GET_CB_FN

  Description: get callback function pointer (if NULL, action is synchronous)

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pCb_fn(m2mb_uart_ind_callback *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_CB_FN, &cb_fn)

• Action: M2MB_UART_IOCTL_SET_CB_USERDATA

  Description: set callback data pointer

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), cbData(void *)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_CB_USERDATA, cbData)

• Action: M2MB_UART_IOCTL_GET_CB_USERDATA

  Description: get callback data pointer

  Params(in): fd(INT32), request(M2MB_UART_IOCTL_REQUEST), pCbData(void **)

  Example: m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_CB_USERDATA, &cbData)

m2mb_uart_ioctl(fd, request, cfg);

int main()
{
  INT32 fd;
  INT32 retVal;
  M2MB_UART_CFG_T cfg;
  fd = m2mb_uart_open("/dev/tty1", 0);
 
  //...
 
  retVal = m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_GET_CFG, &cfg);
  if ( retVal != -1 )
    printf( "m2mb_uart_ioctl: get cfg struct succeeded");
 
  // modify some configuration structure fields...
  cfg.baud_rate = 9600;
  //...
 
  retVal = m2mb_uart_ioctl(fd, M2MB_UART_IOCTL_SET_CFG, &cfg);
  if ( retVal != -1 )
    printf( "m2mb_uart_ioctl: set cfg struct succeeded");
 
}

m2mb_uart_open()

INT32 m2mb_uart_open	(	const CHAR *	path,
		INT32	flags,
			...
	)

m2mb_uart_open opens a UART device.

m2mb_uart_open opens a UART device returning the file descriptor that must be passed as first parameter for all the other UART actions. Calling the m2mb_uart_open is mandatory before using the UART device.

Parameters

[in]	path	first parameter is the path to the UART device, that will be initialized by the function. It is a string like "/dev/ttyX" where X is the UART instance index. Path "/dev/tty" is equivalent to default "/dev/tty0".
[in]	flags	second parameter is the access mode flags. Currently unused

Returns

returns the File Descriptor on SUCCESS, -1 on FAILURE.

Note

A default configuration is applied, with following values:

• Baud rate: 115200 bps
• Flow Control: off
• Parity Mode: none
• Stop Bits: 1
• Bits Per Char: 8
• Loopback Mode: disabled
• Synchronous Write Timeout: 0 ms
• Synchronous Read Timeout: 0 ms
• Callback Function: none
• Callback Data: none

m2mb_uart_open(path, flags);

int main()
{
  INT32 fd;
  fd = m2mb_uart_open("/dev/tty1", 0);
  if ( fd != -1 )
    printf( "m2mb_uart_open succeeded");
}

m2mb_uart_read()

SSIZE_T m2mb_uart_read	(	INT32	fd,
		void *	buf,
		SIZE_T	nbyte
	)

m2mb_uart_read reads data from an open UART device.

m2mb_uart_read reads up to nbyte Bytes from a UART device into a destination buffer.

Parameters

[in]	fd	first parameter is the File Descriptor returned by m2mb_uart_open()
[in]	buf	second parameter is the destination buffer, previously allocated.
[in]	nbyte	third parameter is the length of the destination buffer in Bytes.

Returns

returns the number of read Bytes on SUCCESS, -1 on FAILURE.

Note

Reading can be synchronous or asynchronous. If the callback has been registered (by means of m2mb_uart_ioctl), the function m2mb_uart_read() has an asynchronous behavior: when new data is available from the UART device, the registered callback is triggered in order to signal that a not blocking reading can be performed. If no callback has been registered, the function m2mb_uart_read() has a synchronous behavior and the reading remains blocked until new data is available from the UART device or for a timeout set by means of m2mb_uart_ioctl.

m2mb_uart_read(fd, buf, nbyte);

#define BUF_LEN 32
int main()
{
  INT32 fd;
  INT32 rdBytes;
  UINT8 dstBuf[BUF_LEN];
  fd = m2mb_uart_open("/dev/tty1", 0);
 
  //...
 
  rdBytes = m2mb_uart_read(fd, dstBuf, BUF_LEN);
  if ( rdBytes >= 0 )
    printf( "m2mb_uart_read succeeded");
}

m2mb_uart_write()

SSIZE_T m2mb_uart_write	(	INT32	fd,
		const void *	buf,
		SIZE_T	nbyte
	)

m2mb_uart_write writes data to an open UART device.

m2mb_uart_write writes nbyte Bytes from a source buffer to a UART device.

Parameters

[in]	fd	first parameter is the File Descriptor returned by m2mb_uart_open()
[in]	buf	second parameter is the source buffer, previously allocated.
[in]	nbyte	third parameter is the length of the source buffer in Bytes.

Returns

returns the number of written Bytes on SUCCESS, -1 on FAILURE.

Note

Writing can be synchronous or asynchronous. If the callback has been registered (by means of m2mb_uart_ioctl), the function m2mb_uart_write() has an asynchronous behavior: after a not blocking writing has been performed, the registered callback is triggered in order to signal that the whole data has been successfully transmitted to the UART device. If no callback has been registered, the function m2mb_uart_write() has a synchronous behavior and the wtiting remains blocked until the data transmission to the UART device is completed or for a timeout set by means of m2mb_uart_ioctl.

m2mb_uart_read(fd, buf, nbyte);

#define BUF_LEN 32
#define WR_BYTE_VAL 0xAB
int main()
{
  INT32 fd;
  INT32 wrBytes;
  UINT8 srcBuf[BUF_LEN];
  fd = m2mb_uart_open("/dev/tty1", 0);
 
  //...
 
  memset(srcBuf, WR_BYTE_VAL, BUF_LEN);
  wrBytes = m2mb_uart_write(fd, srcBuf, BUF_LEN);
  if ( wrBytes >= 0 )
    printf( "m2mb_uart_write succeeded");
}