logback.xml

<configuration>
  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
      <file>/sdcard/Medtronic640gUploader.log</file>
    <append>true</append>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <fileNamePattern>/sdcard/Medtronic640gUploader.%i.log.zip</fileNamePattern>
      <minIndex>1</minIndex>
      <maxIndex>3</maxIndex>
    </rollingPolicy>

    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>5MB</maxFileSize>
    </triggeringPolicy>
   
    <encoder>
      <pattern>%-5p[%d{yyyy-MM-dd HH:mm:ss}]:%msg%n</pattern>
    </encoder>
  </appender>

  <root level="ERROR">
    <appender-ref ref="FILE" />
  </root>
</configuration>