Documentation/Maemo 5 Developer Guide/Using Multimedia Components/FM Transmitter API Usage

(Properties: clarified possible 'state' values)
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FM Transmitter is controlled by <code>fmtx-middleware</code> program via D-Bus API. API includes functions to enable transmitter, change transmitting frequency and station name. Please note that available frequencies may vary by sales region and FM Transmitter may be disabled in certain sales regions. Transmitter is also disabled when external devices are connected to Maemo device, excluding charger and Bluetooth devices. When FM Transmitter is enabled, fmtx-middleware will route audio automatically to the transmitter and enforce proper transmission power allowed in sales region. Fmtx-middleware will emit beeping tone when no other audio is being transmitter to comply with legislature. Api documentation is in the fmtx-middleware-doc package.
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The [[N900 FM radio transmitter|FM Transmitter]] is controlled by <code>fmtx-middleware</code> program via D-Bus API. API includes functions to enable transmitter, change transmitting frequency and station name. Please note that available frequencies may vary by sales region and FM Transmitter may be disabled in certain sales regions. Transmitter is also disabled when external devices are connected to Maemo device, excluding charger and Bluetooth devices. When FM Transmitter is enabled, fmtx-middleware will route audio automatically to the transmitter and enforce proper transmission power allowed in sales region. Fmtx-middleware will emit beeping tone when no other audio is being transmitter to comply with legislature. API documentation is in the [http://maemo.org/packages/view/fmtx-middleware-doc/ fmtx-middleware-doc] package.
== API documentation ==
== API documentation ==
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Object path: /com/nokia/fmtx/default
Object path: /com/nokia/fmtx/default
</pre>
</pre>
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===Properties===
===Properties===
{| class="wikitable"
{| class="wikitable"
-
| version
+
| <code>version</code>
| Uint32
| Uint32
| Read only
| Read only
| Version number of <code>fmtx-middleware</code>
| Version number of <code>fmtx-middleware</code>
|-
|-
-
| frequency
+
| <code>frequency</code>
| Uint32
| Uint32
| Read/write
| Read/write
| Frequency in kHz. Returns <code>DBUS_GERROR_INVALID_ARGS</code> error, if frequency is not allowed
| Frequency in kHz. Returns <code>DBUS_GERROR_INVALID_ARGS</code> error, if frequency is not allowed
|-
|-
-
| freq_max
+
| <code>freq_max</code>
| Uint32
| Uint32
| Read only
| Read only
| Returns maximum allowed frequency in kHz
| Returns maximum allowed frequency in kHz
|-
|-
-
| freq_step
+
| <code>freq_step</code>
| Uint32
| Uint32
| Read only
| Read only
| Returns the minimum step between frequencies in kHz
| Returns the minimum step between frequencies in kHz
|-
|-
-
| state
+
| <code>state</code>
| String
| String
| Read/write
| Read/write
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May return <code>DBUS_GERROR_FAILED</code> if transmitter can’t be enabled
May return <code>DBUS_GERROR_FAILED</code> if transmitter can’t be enabled
|-
|-
-
| startable
+
| <code>startable</code>
| String
| String
| Read only
| Read only
| Returns message about can the transmitter be enabled at current time. Messages are: true Device is in offline mode Headphones are connected USB device is connected
| Returns message about can the transmitter be enabled at current time. Messages are: true Device is in offline mode Headphones are connected USB device is connected
|-
|-
-
| rds_ps
+
| <code>rds_ps</code>
| String
| String
| Read/write
| Read/write
| Get/Set RDS Station name (displayed on rds capable radios). To avoid problems with some radios, use text which length is dividable by 8. Pad with spaces if necessary
| Get/Set RDS Station name (displayed on rds capable radios). To avoid problems with some radios, use text which length is dividable by 8. Pad with spaces if necessary
|-
|-
-
| rds_text
+
| <code>rds_text</code>
| String
| String
| Read/write
| Read/write
-
| Get/Set RDS text (displayed alternating with station name. Maximum length is 64 characters. Returns <code>DBUS_GERROR_INVALID_ARGS</code> is set text is too long
+
| Get/Set RDS text (displayed alternating with station name. Maximum length is 64 characters. Returns <code>DBUS_GERROR_INVALID_ARGS</code> is set if the text is too long
|}
|}
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{| class="wikitable"
{| class="wikitable"
-
| Changed
+
| <code>Changed</code>
| None
| None
| Some fmtx property was changed
| Some fmtx property was changed
|-
|-
-
| Error
+
| <code>Error</code>
| String
| String
| FM transmitter was disabled by one of the following reasons: <ul><li>Device entered offline mode</li><li>USB device was connected (excluding charger)</li><li>Headphones were connected</li><li>TV-Out cable was connected</li></ul>
| FM transmitter was disabled by one of the following reasons: <ul><li>Device entered offline mode</li><li>USB device was connected (excluding charger)</li><li>Headphones were connected</li><li>TV-Out cable was connected</li></ul>

Revision as of 15:54, 6 September 2010


The FM Transmitter is controlled by fmtx-middleware program via D-Bus API. API includes functions to enable transmitter, change transmitting frequency and station name. Please note that available frequencies may vary by sales region and FM Transmitter may be disabled in certain sales regions. Transmitter is also disabled when external devices are connected to Maemo device, excluding charger and Bluetooth devices. When FM Transmitter is enabled, fmtx-middleware will route audio automatically to the transmitter and enforce proper transmission power allowed in sales region. Fmtx-middleware will emit beeping tone when no other audio is being transmitter to comply with legislature. API documentation is in the fmtx-middleware-doc package.

Contents

API documentation

Service: com.nokia.FMTx
Interface: com.nokia.FMTx.Device
Object path: /com/nokia/fmtx/default

Properties

version Uint32 Read only Version number of fmtx-middleware
frequency Uint32 Read/write Frequency in kHz. Returns DBUS_GERROR_INVALID_ARGS error, if frequency is not allowed
freq_max Uint32 Read only Returns maximum allowed frequency in kHz
freq_step Uint32 Read only Returns the minimum step between frequencies in kHz
state String Read/write Returns the state of the transmitter. States are:
  • enabled – Transmitter is currently enabled
  • disabled – Transmitter is currently disabled
  • error – Internal error while initializing the transmitter, transmitter can’t be enabled.
  • n/a – Transmitter is permanently disabled in this device.

State can be set to enabled or disabled. May return DBUS_GERROR_FAILED if transmitter can’t be enabled

startable String Read only Returns message about can the transmitter be enabled at current time. Messages are: true Device is in offline mode Headphones are connected USB device is connected
rds_ps String Read/write Get/Set RDS Station name (displayed on rds capable radios). To avoid problems with some radios, use text which length is dividable by 8. Pad with spaces if necessary
rds_text String Read/write Get/Set RDS text (displayed alternating with station name. Maximum length is 64 characters. Returns DBUS_GERROR_INVALID_ARGS is set if the text is too long

Signals

Changed None Some fmtx property was changed
Error String FM transmitter was disabled by one of the following reasons:
  • Device entered offline mode
  • USB device was connected (excluding charger)
  • Headphones were connected
  • TV-Out cable was connected

Properties are manipulated with org.freedesktop.DBus.Properties interface. For more information see D-Bus documentation.