SUOTA流程

蓝牙升级流程

1. 发起者往外围设备特征SPOTA_MEM_DEV_UUID写值来设置内存类型(memoryType)

// Step 1: Set memory type
step = 0;
expectedValue = 0x10;
nextStep = 2;
int _memDevData = (self.memoryType << 24) | (self.memoryBank & 0xFF);
[self debug:[NSString stringWithFormat:@"Sending data: %#10x", _memDevData]];
NSData *memDevData = [NSData dataWithBytes:&_memDevData length:sizeof(int)];
// 往特征写值成功后将回调两个方法
[manager writeValue:[manager IntToCBUUID:SPOTA_SERVICE_UUID]
characteristicUUID:[CBUUID UUIDWithString:SPOTA_MEM_DEV_UUID]
p:manager.device data:memDevData];

2. 发起者往外围设备特征SPOTA_GPIO_MAP_UUID写值设置存储器参数

• 存储器的总线接口有SPI/I2C

int _memInfoData
if (self.memoryType == MEM_TYPE_SUOTA_SPI) {
     _memInfoData = (self.spiMISOAddress << 24) | (self.spiMOSIAddress << 16) | (self.spiCSAddress << 8) | self.spiSCKAddress;
} else if (self.memoryType == MEM_TYPE_SUOTA_I2C) {
     _memInfoData = (self.i2cAddress << 16) | (self.i2cSCLAddress << 8) | self.i2cSDAAddress;
}

• 往特征SPOTA_GPIO_MAP_UUID写值

[manager writeValue:[manager IntToCBUUID:SPOTA_SERVICE_UUID] characteristicUUID:[CBUUID UUIDWithString:SPOTA_GPIO_MAP_UUID] p:manager.device data:memInfoData];

3. 加载镜像数据，进行循环冗余码校验（CRC）并设置每次发送的数据大小(chunkSize)以及镜像的起始字节(blockStartByte)。

• 加载镜像数据

[self debug:[NSString stringWithFormat:@"Loading data from %@", [storage.file_url absoluteString]]];
fileData = [[NSData dataWithContentsOfURL:storage.file_url] mutableCopy];

• 进行循环冗余码校验

[self appendChecksum];

• chunkSize & blockStartByte

chunkSize = 20;
blockStartByte = 0;

4. 发起者往外围设备特征SPOTA_PATCH_LEN写值来指定块长度，以此来告诉接收者镜像的数据块长度。

• 往特征SPOTA_PATCH_LEN_UUID写值设置镜像长度数据

NSData *patchLengthData = [NSData dataWithBytes:&blockSize length:sizeof(UInt16)];
[manager writeValue:[manager IntToCBUUID:SPOTA_SERVICE_UUID] characteristicUUID:[CBUUID UUIDWithString:SPOTA_PATCH_LEN_UUID] p:manager.device data:patchLengthData];

blockSize是发送镜像的数据块大小，默认是240字节。

5. 发起者往外围设备特征SPOTA_PATCH_DATA发送镜像数据（以blockSize(240kb)为一个单位），重复发送镜像数据每次发送chunkSize字节(20kb)。

• 每发送完成一个单位的镜像数据就执行更新特性的方法来判断是否出现错误，通过characteristic.value调用getByte:length方法得到结果信息，失败弹窗提示错误，成功则log日志并重复执行第五步骤。

- (void) didUpdateValueForCharacteristic: (NSNotification*)notification {
    CBCharacteristic *characteristic = (CBCharacteristic*) notification.object;
    if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:SPOTA_SERV_STATUS_UUID]]) {
        char value;
        [characteristic.value getBytes:&value length:sizeof(char)];
        NSString *message = [self getErrorMessage:value];
        [self debug:message];
        // 通过第五步骤跳转到此方法，expectedValue = 0x02
        if (expectedValue != 0) {
            // Check if value equals the expected value
            if (value == expectedValue) { // 得到期望值
                // If so, continue with the next step
                step = nextStep; // 通过第五步骤跳转到此方法，nextStep = 5
                expectedValue = 0; // Reset
                [self doStep];
            } else { // 出现错误
                // Else display an error message
                UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error" message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
                [alertView show];
                expectedValue = 0; // Reset
                [autoscrollTimer invalidate]; // 关闭刷新textView的大小
            }
        }
    }
}

• 当发送完N个blockSize大小的数据，剩余镜像数据为bytesRemaining。
  
  • I.当chunkStartByte(局部变量，初始化为0，每次累加20)大于或等于blockSize时，则更新镜像起始块大小(blockStartByte，全局变量，初始化为0)。
  • I.当bytesRemaining < blockSize时，让blockSize = bytesRemaining并跳转到第四步(step = 4)，重新设置镜像块大小。
  • II.当bytesRemaining = 0时，跳转到第六步发送结束命令并跳转到第七步提示用户是否重启外围设备。

// On to the chunk
chunkStartByte += chunkSize;
// Check if we are passing the current block
if (chunkStartByte >= blockSize) {
// Prepare for next block
   blockStartByte += blockSize;
   int bytesRemaining = dataLength - blockStartByte;
   if (bytesRemaining == 0) {
       nextStep = 6;
   } else if (bytesRemaining < blockSize) {
       blockSize = bytesRemaining;
       nextStep = 4; // Back to step 4, setting the patch length
   }
}

6. 发起者往外围设备特征SPOTA_MEM_DEV_UUID发送结束指令，并跳转到第七步。

// Send SUOTA END command
step = 0;
expectedValue = 0x02;
nextStep = 7;
int suotaEnd = 0xFE000000;
[self debug:[NSString stringWithFormat:@"Sending data: %#10x", suotaEnd]];
NSData *suotaEndData = [NSData dataWithBytes:&suotaEnd length:sizeof(int)];
[manager writeValue:[manager IntToCBUUID:SPOTA_SERVICE_UUID] characteristicUUID:[CBUUID UUIDWithString:SPOTA_MEM_DEV_UUID] p:manager.device data:suotaEndData];

7. 弹框让用户选择是否重启外围设备，如果选择重启则向外围设备特征SPOTA_MEM_DEV_UUID发送重启指令。

if (buttonIndex != alertView.cancelButtonIndex) {
    // Send reboot signal to device
    step = 8; // 返回到扫描设备的界面
    int suotaEnd = 0xFD000000;
    [self debug:[NSString stringWithFormat:@"Sending data: %#10x", suotaEnd]];
     NSData *suotaEndData = [NSData dataWithBytes:&suotaEnd length:sizeof(int)];
     [manager writeValue:[manager IntToCBUUID:SPOTA_SERVICE_UUID] characteristicUUID:[CBUUID UUIDWithString:SPOTA_MEM_DEV_UUID] p:manager.device data:suotaEndData];
}