GRAPHICS CONTROLLERS INDIGO SOUND GENERATOR

Transcription

1 Fujitsu Microelectronics Europe Application Note an-mb88f332-sg-cfgfifo-rev0-20 GRAPHICS CONTROLLERS MB88F332 'INDIGO' INDIGO SOUND GENERATOR APPLICATION NOTE GRAPHICS COMPETENCE CENTER

2 Revision History Revision History Date Issue Rev 0.01 GCC/VTh First draft Rev 0.10 GCC/HA Layout, added introduction, 1 st and 2 nd chapter reworked Rev 0.20 GCC/HA First release This document contains 13 pages. an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

3 Warranty and Disclaimer Warranty and Disclaimer To the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH restricts its warranties and its liability for all products delivered free of charge (eg. software include or header files, application examples, target boards, evaluation boards, engineering samples of IC s etc.), its performance and any consequential damages, on the use of the Product in accordance with (i) the terms of the License Agreement and the Sale and Purchase Agreement under which agreements the Product has been delivered, (ii) the technical descriptions and (iii) all accompanying written materials. In addition, to the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH disclaims all warranties and liabilities for the performance of the Product and any consequential damages in cases of unauthorised decompiling and/or reverse engineering and/or disassembling. Note, all these products are intended and must only be used in an evaluation laboratory environment. 1. Fujitsu Microelectronics Europe GmbH warrants that the Product will perform substantially in accordance with the accompanying written materials for a period of 90 days form the date of receipt by the customer. Concerning the hardware components of the Product, Fujitsu Microelectronics Europe GmbH warrants that the Product will be free from defects in material and workmanship under use and service as specified in the accompanying written materials for a duration of 1 year from the date of receipt by the customer. 2. Should a Product turn out to be defect, Fujitsu Microelectronics Europe GmbH s entire liability and the customer s exclusive remedy shall be, at Fujitsu Microelectronics Europe GmbH s sole discretion, either return of the purchase price and the license fee, or replacement of the Product or parts thereof, if the Product is returned to Fujitsu Microelectronics Europe GmbH in original packing and without further defects resulting from the customer s use or the transport. However, this warranty is excluded if the defect has resulted from an accident not attributable to Fujitsu Microelectronics Europe GmbH, or abuse or misapplication attributable to the customer or any other third party not relating to Fujitsu Microelectronics Europe GmbH. 3. To the maximum extent permitted by applicable law Fujitsu Microelectronics Europe GmbH disclaims all other warranties, whether expressed or implied, in particular, but not limited to, warranties of merchantability and fitness for a particular purpose for which the Product is not designated. 4. To the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH s and its suppliers liability is restricted to intention and gross negligence. NO LIABILITY FOR CONSEQUENTIAL DAMAGES To the maximum extent permitted by applicable law, in no event shall Fujitsu Microelectronics Europe GmbH and its suppliers be liable for any damages whatsoever (including but without limitation, consequential and/or indirect damages for personal injury, assets of substantial value, loss of profits, interruption of business operation, loss of information, or any other monetary or pecuniary loss) arising from the use of the Product. Should one of the above stipulations be or become invalid and/or unenforceable, the remaining stipulations shall stay in full effect Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20

4 Contents Contents REVISION HISTORY... 2 WARRANTY AND DISCLAIMER... 3 CONTENTS INTRODUCTION SG USE WITHOUT CONFIG FIFO SG USE TOGETHER WITH CONFIG FIFO BEHAVIOUR OF THE SOUND GENERATOR REFERENCES an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

5 Chapter 1 Introduction 1 Introduction This application note describes the use of the sound generator module (SG) of the MB88F332 'Indigo' device, referred to as 'Indigo' within this document. The sound generator has 2 'main' operation modes. The first is essentially the same as in the 460 Series of Fujitsu's MCU products. The second mode is the use of the module in conjunction with Indigo s internal Configuration FiFo (CFGFiFo). Please bear in mind that in both cases, the Indigo is controlled by an external MCU (controller), either via APIX or via the HOST Interface. This has an impact on the module's latency in general. In comparison to the MCU's sound module being used, which has a static and predicable/calculateable latency, the usage of the sound generator module in Indigo adds an inherent latency that can vary within a certain range. You must have a correct setup to avoid sound jitter, which will otherwise be heard as audible artefacts. Please keep this in mind when designing your application, i.e. take into account which structure the sound should have, in terms of pauses or consecutive waveforms, changes of amplitudes, frequencies, single or multiple tones etc. Consider the workload on the MCU as well and choose to use the SG with CFGFiFo or direct control via the MCU accordingly. To give you a better understanding of the constraints for both modes, please read the following chapters. Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20

6 Chapter 2 SG use without Config FiFo 2 SG use without Config FiFo The MCU application note mcu-an e-mb91460 [2] describes the generation of tone sequences (melodies) with the SG module integrated in 460 MCU series devices. This described configuration could be used for the SG module in Indigo as well, BUT some constraints have to be taken into consideration: Latency is added to the control path, on both the HOST Interface and the APIX Link. Control via the MCU gives you the flexibility to choose and manipulate all the parameters for each tone that is going to be played next at runtime. Each single tone is defined by a certain number of registers that are send to the Indigo, but no buffer can be used in that case. Moreover continuous tones may will have audible artefacts if the latency becomes too big. If the sound structure continually contains pauses between the single tones this approach could be used easily. In other cases the next four steps must be followed to get a reliable result for each tone. 1) the SG must be stopped by software (ST=0) (register SGCRL) 2) wait until the busy flag equals 0 3) reprogram the SGFR, SGAR, SGTR, SGDR registers 4) restart the SG (ST=1) (register SGCRL) Step 1) If the SG is not stopped and registers are rewritten, disturbances will occur in the output. They can be audible or not, depending entirely on the structure of the tone being played. Step 2) Can be realized via a polling function on the corresponding register but will add load on the link and on the controller. If the exact structure of the sound is known and suitable (pauses or continuous sounds with matching amplitudes), the transmission of the data from the MCU in certain timeframes might be possible as well. A state machine/control logic also could be implemented on the controller side to make sure that the SG module is fed according to the specification. Step 3) Has no restrictions besides the register width and access methods in Indigo. Please see Appnote concerning Endianess too. Step 4) Restarting the SG after setting all data registers will ensure proper output. an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

7 Chapter 3 SG use together with Config FiFo 3 SG use together with Config FiFo The MCU application note mcu-an e-mb91460 [2] describes the generation of tone sequences (melodies) with the SG module of the 460 MCU series. The described program flow must be adapted for the use with the Indigo CFGFIFO. This scenario should be used if you want to transfer a number of tones to the Indigo FiFo at a given time (to preload and buffer them in Indigo). This sequence can later be started/triggered by a single command and then continuously fed by the MCU using all the features of the ConfigFiFo module to prevent any jitter in the transmission line. Please read the chapter Configuration FiFO in the Indigo Hardware Manual for more details. By design, the continuous output of the FiFo has a certain impact on the sound output. The main reason is that to reprogram the SG, the following sequence must be used: 1) the SG must be stopped by software (ST=0) (register SGCRL) 2) wait until busy=0 3) reprogram the SGFR, SGAR, SGTR, SGDR registers 4) restart the SG (ST=1) (register SGCRL) This sequence is not possible with the simple DMA functionality provided by the CFGFiFo. CChecking the busy flag can not be done via the module but it is included implicitly by the fact that triggering the FiFo is only done when the tone has nearly finished. Nevertheless, the ST = 0 setting would generally stop the transfer from the FiFo to the SG module. With the CFGFIFO, it is only possible to implement the sequence 3) + 4). This means that the SG is reprogrammed during operation. The reload values for the four counters are changed during operation. which has the consequence that the counters for the new tone receive their values with a certain delay. These delays are discussed in the following chapter. Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20

8 Chapter 4 Behaviour of the Sound Generator 4 Behaviour of the Sound Generator Using an example, the following diagram visualizes the behaviour of the SG module if it is programmed without being stopped first (busy=1). The example shows four updates, updates 2-4 are handled by the CFGFIFO module, update 1 is done by normal upfront access. Characteristic for the reprogramming by the CFGFIFO is that this happens immediately after the SG interrupt (=trigger for CFGFIFO), that means always during the low phase of the SGO output. Figure 4-1, Example Notes: 1. Frequency change (SGFR) becomes active with next edge (rising or falling) of the SGO signal after the trigger 2. Amplitude change (SGAR) becomes active with the next falling edge of the SGO signal (not mixed) after the trigger. The same is valid for the DEC (decrement enable) bit. 3. Length change (SGTR) becomes active with the next trigger. This means a delay of one complete tone 4. Decrement Grade change (SGDR) becomes active after SGDR(t-1)+1 falling edges of the signal SGO (not mixed) after the trigger. 5. (As documented) If DEC=1 and SGDR>0 then the amplitude is decremented if the decrement grade counter is finished 6. (As documented) Stop command an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

9 Chapter 4 Behaviour of the Sound Generator 7. SGO and SGA output are stopped with the next falling edge of SGO (not mixed) after trigger (one period after trigger). When changing the SGTR register, item 3 in the list above causes an audible effect, because the tone is played with the wrong tone duration. Also list item 4 causes a different tone length to that expected. The exact tone duration (time between two SG triggers) can be calculated using the following formula: baseperiod = 1/(83.3MHz / 2 / prescaler / 256 / 2) Equation 4-1 tonelength( in baseperiods) = ( SGFR( + 1) ((( SGDR( + 1) SGTR( t 1)) + SGDR( t 1)) 0.5 ( SGFR( + 1) ( SGFR( t 1) + 1) Equation 4-2 If SGTR >> 0 the following formula can be used for an approximate value tone length( in baseperiods) = ( SGFR( + 1) ((( SGDR( + 1) SGTR( t 1)) + SGDR( t 1)) Equation 4-3 This can be further approximated if the difference between SGDR( and SGDR(t-1) is small tone length( in baseperiods) = ( SGFR( + 1) (( SGDR( + 1) ( SGTR( t 1) + 1)) Equation 4-4 List items 1 and 2 are generally not audible. But when changing amplitudes and tones with very low frequencies the non-ideal waveform (frequency of new tone is output together with the amplitude of the old tone for one period) audible effects can be observed. This also depends also on the loudspeaker and external circuitry in use. Workaround 1 for list item 3: The workaround is based on Equation 4-4, which is the same as the formula of the SG module specification (SGTR register description), except for the time index of SGTR. Therefore program the SGTR register one tone before the related SGAR, SGFR, SGDR registers. This has the consequence that the first tone of the presetup already determines the tone length of the second tone. Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20

10 Chapter 4 Behaviour of the Sound Generator To avoid this influence, split the first tone into 2-3 single tones with same frequency and amplitude. 1. Program tone 1a directly (presetup of SG-module): frequency f1, length 1, amplitude = a1 2. Start SG with SGCRL.ST=1 3. CFGFIFO programs tone 1b: frequency f1, length l1-2, amplitude = a1 4. CFGFIFO programs tone 1c: frequency f1, length l2, amplitude = a1 Or when length l1 is even: 1. Program tone 1a directly (pre-setup of SG-module): frequency f1, length l1/2, amplitude = a1 2. Start SG with SGCRL.ST=1 3. CFGFIFO programs tone 1b: frequency f1, length l2, amplitude = a1 Disadvantages/Limitations: The first tone has always a minimum of two frequency periods The effects of list items 1,2 and 4 may be audible for low frequencies Workaround 2 This workaround reduces the effect of list items 1 and 2 if the external circuitry uses only the mixed SGO output. SGA is not used. Between tones with changing amplitudes, insert one tone with a length of one unit. Program the tone length and amplitude one tone before the frequency is programmed. Use the decrement grade register only if you can compensate list item 4 (not shown in example). Example: an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

11 Chapter 4 Behaviour of the Sound Generator Disadvantage: Only the mixed SGO signal output can be used, external circuitry which uses the benefits of SGA would show a similar effect to workaround 1. Workaround 3: (proposal) Inserting pauses (tones with amplitude 0) Disadvantage: Pauses no continuous output Minimum length of a pause is 1 period of the highest frequency counter value used. Workaround 4: (proposal) Use the CFGFIFO only to stop the output (ST=0) Use the Interrupt Service Routine ISR of the MCU to program the next tone. Advantage: similar behaviour to that described in MCU SG Appnote mcu-an emb91460 [2] Disadvantage: A short pause is audible between the two tones. The pause length is influenced by the interrupt reaction time. This depends on the variable latency of the APIX link (up and down) and the MCU load. Workaround 5: (proposal) Use the CFGFIFO to trigger a command sequence which programs the following sequence: 1) SGCRL.ST=0 2) Wait for a constant time (minimum time = period of lowest frequency tone, which is used) 3) Reprogram the SGFR, SGAR, SGTR, SGDR registers 4) SGCRL.ST=1 Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20

12 Chapter 4 Behaviour of the Sound Generator The different tone sequences can be stored either in the embedded SRAM or flash memory of Indigo. The start addresses for the command sequence are programmed by the CFGFIFO before activating the Command Sequencer. Disadvantage/Limitations: Software triggered command sequences have the lowest priority. Therefore they can be interrupted by e.g. Signature or 'no signal' screen command sequences. an-mb88f332-sg-cfgfifo -rev Fujitsu Microelectronics Europe GmbH

13 Chapter 5 References 5 References [1] MB88F332, LSI Product Specification, FUJITSU Microelectronics Europe GmbH [2] mcu-an e-mb91460_sound_generation/mcu-an e-v10- mb91460_sound_generation.pdf Fujitsu Microelectronics Europe GmbH an-mb88f332-sg-cfgfifo -rev0-20