ESP32 Forum

@ESP_Sprite,

The LCD_CAM in "FIFO MODE" it's kinda buggy.

I should be able to send up to 8192 bytes, lcd_dout_cyclelen : R/W; bitpos: [12:0] The output data cycles minus 1 of LCD module, uint32_t lcd_dout_cyclelen: 13, but:

ESP_Sprite: "Note that the FIFO data register is 9-bit, with bit 8 the EOF bit, so I think you should be able to set the 9th bit of the last byte you push and you'd not have to send any dummy bits."

If i send 0x0155 in the outfifo_wdata register, ie: set bit 8 the EOF bit, the maximum bytes i can send is 35 bytes.
I am sending only data, not command.
https://youtu.be/VG3-5WsuCXE

If i send 0x0155 in the outfifo_wdata register, ie: set bit 8 the EOF bit and only multiples of 8 bytes(8,16,24....), the maximum bytes i can send is 32 bytes.
I am sending only data, not command.
https://youtu.be/bXST7Qc5BwU

If i send 0x0055 in the outfifo_wdata register, ie: NOT set bit 8 the EOF bit and only multiples of 8 bytes(8,16,24....), the maximum bytes i can send is 112 bytes.
I am sending only data, not command.
https://youtu.be/y2WWADsgrH4

From now, i will try to use dma("DMA_MODE").

@ESP_Sprite,

How can i control cs(chip select) pin using LCD_CAM module ?
Without using direct gpio manipulation !!!

In Technical Reference Manual v0.4 page 530, Table 24-1. Signal Description, show LCD Master Tx Mode,
LCD_CS Output Chip select (CS) signal in I8080/MOTO6800 format

Thank's.

@ESP_Sprite,

What is the frequency of the GDMA clock ?

I don't think i can configure this frequency, but it doesn't hurt to ask.

Thank's.

I don't think you can, not directly at least. GDMA transfers generally go at the speed of the APB clock (=80MHz in most cases)

Regarding chip select ?

@ESP_Sprite,

How can i control cs(chip select) pin using LCD_CAM module ?
Without using direct gpio manipulation !!!

In Technical Reference Manual v0.4 page 530, Table 24-1. Signal Description, show LCD Master Tx Mode,
LCD_CS Output Chip select (CS) signal in I8080/MOTO6800 format

Thank's.

@ESP_Sprite,

Forget about it, i fixed it.

I had not connected the io cs pin to the LCD_CAM module.

I relied on the example "esp_lcd_panel_io_i80.c", and that example not connect chip select pin, only clock, dc, and data.

@ESP_Sprite,

I am trying to use spiram with LCD_CAM and GDMA.

Apparently it's working (I haven't tested it on the lcd yet), with 20 Mhz lcd i8080 clock, 8 bit bus.

Three Questions:

1) What is the frequency limit in this configuration ?
OBS: above of 20Mhz(external lcd clock) is not working(apparently the LCD_CAM or GDMA module is crashing).
In esp32-s3 thecnical reference manual v0.4 only describes with internal memory(static memory), 80 Mhz. Page 541.

2) Do i need to release some permission to access spiram ?
OBS: External RAM Access Permissions.
In esp32-s3 thecnical reference manual v0.4, 2.4.10 External RAM Access Permissions, page 82.

3) Do i need to enable EDMA ?
OBS: SYSTEM_EDMA_CTRL_REG.
In esp32-s3 thecnical reference manual v0.4, 13.3.5 Peripheral Clock Gating and Reset Registers, page 326.

Hardware:
Current hardware: ESP32-S3-DevKitC-1 with ESP32-S3-WROOM-1-N8R8.
Future hardware: i will test with ESP32-S3-DevKitC-1 with ESP32-S3-WROOM-2-N32R8V.

OBS: "External" spiram stay inside esp32-s3 chip in N8R8 and N32R8V.

Thank's.

1. I'm not sure. You should be able to get the frequency limits from the TRM, but there is also a bandwidth limit if you want to access PSRAM using the CPU as well, and I'm looking for docs with those calculations. If you use internal memory as a buffer, you can probably use any frequency the hardware allows as the bandwidth to that is way bigger.
2. I don't think so, it should be open by default.
3. If you need to feed the LCD from PSRAM, then yes, you need EDMA to be enabled.

@ESP_Sprite,

Can you get the information from item 1 with the digital team ?

I need to know if the limit is 20 Mhz or if my program has a bug in this configuration.

If i want to use big buffers, the spiram are the only option to go.

I will test the lcd refresh speed with static ram and with spiram later.

1. I'm not sure. You should be able to get the frequency limits from the TRM, but there is also a bandwidth limit if you want to access PSRAM using the CPU as well, and I'm looking for docs with those calculations. If you use internal memory as a buffer, you can probably use any frequency the hardware allows as the bandwidth to that is way bigger.
2. I don't think so, it should be open by default.
3. If you need to feed the LCD from PSRAM, then yes, you need EDMA to be enabled.

@ESP_Sprite,

Item 3:
I think EDMA is enable by default(power on reset), but if i want to set this bits, how should i proceed ?

I tried like this, but get error: undefined reference to `SYSTEM'