spi_ext.go

// Copyright 2014 Krishna Raman
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package firmata

type SPISubCommand byte

// Enable SPI communication for selected chip-select pin
func (c *FirmataClient) SPIConfig(csPin byte, spiMode byte) (err error) {
	csPinBytes := to7Bit(csPin)
	spiModeBytes := to7Bit(spiMode)
	c.spiChan = make(chan []byte)

	err = c.sendSysEx(SysExSPI, byte(SPIConfig),
		csPinBytes[0], csPinBytes[1],
		spiModeBytes[0], spiModeBytes[1])
	return
}

// Read and write data to SPI device
func (c *FirmataClient) SPIReadWrite(csPin byte, data []byte) (dataOut []byte, err error) {
	csPinBytes := to7Bit(csPin)
	data7Bit := []byte{byte(SPIComm)}

	data7Bit = append(data7Bit, csPinBytes...)
	for i := 0; i < len(data); i++ {
		bytes := to7Bit(data[i])
		data7Bit = append(data7Bit, bytes...)
	}

	err = c.sendSysEx(SysExSPI, data7Bit...)
	dataOut = <-c.spiChan
	return
}

func (c *FirmataClient) parseSPIResponse(data7bit []byte) {
	data := make([]byte, 0)
	for i, _ := range data7bit {
		if i >= 3 && i%2 != 0 {
			data = append(data, from7Bit(data7bit[i], data7bit[i+1]))
		}
	}
	c.spiChan <- data
}