Servo - May 2015

Listing 1. Global Variables, Constants, and Objects

// Set up Picadillo display hardware.
 analogWrite(PIN_BACKLIGHT, 255);
 tft.initializeDevice();
 tft.setRotation(0);
 tft.fillScreen(Color::Black);
 tft.setFont(Fonts::Topaz);
 tft.setTextColor(Color::White, Color::Black);
 printCentered(50, "uCAM II 128x128 RGB565 image");
 printCentered(70, "Camera Operation Demonstration");
// Picadill and 4D Systems uCAM II demo.
//
// DLC 3/2015
#include <UTFT.h>

with the uCAM-II command arrays that we might use. This is the same as I used in the MAX32 demo program.

#include <DSPI.h>
#include <TFT.h>

In a typical sketch, the setup() function sets everything up that we will be using in the main loop. Listing 2 is the setup for the Picadillo display.

// Configure the display
PICadillo35t tft;
 
// camera screen "pages"
uint16_t pg1[16384];
 
// Misc.
uint8_t junk;
 
// changing bytes into words for graphics
union {
 uint16_t word;
 uint8_t byte[2];
} convert;

Listing 3 shows the protocol for waking the camera up and getting it ready. Once the uCAM-II is awake, it will only remain awake for 15 seconds if nothing is talking to it. We will be streaming data as fast as we can from it, so it isn’t going to go to sleep on us! This is exactly the same as I used with the MAX32 program in the April issue.

Once again, we will use COM1

Tx/Rx to talk to the camera board.

// Command and status arrays
uint8_t cmd[6];
uint8_t status[6];
uint8_t status2[6];

This sequence is laid out in a flow chart in the uCAM-II documentation.

// Commands
uint8_t INIT[6] = {0xAA,0x01,0x00,0x06,0x09,0x00};
// 16bit 565RGB color raw format
uint8_t GETPIC[6] = {0xAA,0x04,0x02,0x00,0x00,0x00};
// GET PICTURE Raw picture mode
uint8_t RESET[6] = {0xAA,0x08,0x01,0x00,0x00,0x00};
// RESET state machines only
uint8_t HRESET[6] = {0xAA,0x08,0x01,0x00,0x00,0xFF};
// RESET whole camera
uint8_t SYNC[6] = {0xAA,0x0D,0x00,0x00,0x00,0x00};
// wake the camera up
uint8_t ACKF[6] = {0xAA,0x0E,0x0A,0x00,0x00,0x00};
// ACK a complete frame received
uint8_t ACKS[6] = {0xAA,0x0E,0x0D,0x00,0x00,0x00};
// ACK the SYNC response
uint8_t BAUD[6] = {0xAA,0x07,0x02,0x00,0x00,0x00};
// Set BAUD to 1228800

The Picadillo is a 32-bit microcontroller running at 80 MHz, so it can easily out-pace this serial baud rate. To avoid getting ‘-1’ in the data reads, I wait for serial data to become available and when it does, I get it and stuff it into a response array.

Except for the actual picture data, all camera commands and responses

// camera responses to pay attention to in status second byte
#define CDATA 0x0A
#define CSYNC 0x0D
#define CACK 0x0E //byte 3 has the command ID being ACK'd
#define CNACK 0x0F // something bad happened, error in 3rd byte