Sparklet is supported on RH850 series of microcontroller from Renesas. Optimized for Cluster use cases, these MCU’s has in-built GPUs that can support 2.5D graphics.
Sparklet leverages the GPU which in turn depends on the GHS compiler and the RGL library, which are the pre-requisites for Sparklet to run on RH850 MCUs.
It is essential to understand the memory architecture in RH850, RGL and Sparklet to optimize the performance.
Below is the memory map of RH850 D1M1A. The MCU has 3 memory regions of interest:
Internal SRAM starting at address 0xFED80000 for a size of 512 KB.
Video RAM starting at address 0x3FD9C000 for a size of about 2.4MB.
External SDRAM starting at address 0x40000000 for a size dependent on the target board design.
RGL needs at least 4 memory regions for proper operations. For 3 of them, it employs Heaps and manages them via abstraction called the CDI Heap manager (r_cdi_memory.c).
The 4 memory regions are captured in the below table:
Memory Region
Usage
Heap Manager
Typical consumption
IRAM
For general CPU
related operations
IramHeap
30KB
Video RAM
For allocating Video
Memory/general
operations
VramHeap
Based on
configuration
External SDRAM
For allocating Video
Memory/general
operations
SdramHeap
Based on
configuration
Message Queue
Memory
For internal GPU
queue operations
NA
Based on
configuration in
r_util_dhd.h
Sparklet internally uses these heaps to manage its memory so that there is a streamlined access to memory with the CDI Heap Manager remaining the sole master of the memory resource. For any memory assigned via memory pools in Flint, internally the memory block is allocated via the Heap Managers.
Sparklet uses memory pools to manage its memory as captured below.
Pool
Source Heap
Memory Region
Usage
Typical consumption
Internal
SRAM
NA. Direct
Memory via value
IRAM
For allocating
widgets, lookup
table etc. Set via
BMEM_POOL_DEFAULT
macro in
rh850_bsp.c
Based on project
size
Internal
VRAM
VramHeap via
Auto Alloc
Video RAM
Frame buffer
configuration as
set in Flint EFP ->
Memory and
Storage
Based on display
resolution and
configuration
External
SDRAM
SdramHeap via
Auto alloc option
External
SDRAM
Frame buffer
configuration as
set in Flint EFP ->
Memory and
Storage
Based on display
resolution and
configuration
In addition to all these, there might be a need to use capture interface in the design which calls for a separate memory to be set aside for capture buffer.
All these memory regions are configured via a single function called sgui_rh850_mem_init with arguments as below
To give a fair idea, Sparklet does the following internally:
1r_cdi_Heap_tIramHeap; 2 3r_cdi_Heap_tSdramHeap; 4 5r_cdi_Heap_tVramHeap; 6 7R_CDI_InitHeapManager((uint32_t)u32_rh850_iram_base_addr,&IramHeap,0,u32_rh850_iram_block_count,u32_rh850_iram_block_size);// for IRAM 8 9R_CDI_InitHeapManager((uint32_t)u32_rh850_vram_base_addr,&VramHeap,0,u32_rh850_vram_block_count,u32_rh850_vram_block_size);// for VRAM1011R_CDI_InitHeapManager((uint32_t)u32_rh850_sdram_base_addr,&SdramHeap,0,u32_rh850_sdram_block_count,u32_rh850_sdram_block_size);// for SDRAM1213R_UTIL_DHD_Config((dhd_gpu_ptr_t)u32_rh850_video_ram_base_addr,u32_rh850_video_ram_size,&IramHeap);1415R_SYS_DHD_SetCpuHeap(&IramHeap);
