/
max72xx.go
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/
max72xx.go
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// Driver works for max7219 and 7221
// Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf
package max72xx
import (
"machine"
)
type Device struct {
bus machine.SPI
cs machine.Pin
}
// NewDriver creates a new max7219 connection. The SPI wire must already be configured
// The SPI frequency must not be higher than 10MHz.
// parameter cs: the datasheet also refers to this pin as "load" pin.
func NewDevice(bus machine.SPI, cs machine.Pin) *Device {
return &Device{
bus: bus,
cs: cs,
}
}
// Configure setups the pins.
func (driver *Device) Configure() {
outPutConfig := machine.PinConfig{Mode: machine.PinOutput}
driver.cs.Configure(outPutConfig)
}
// SetScanLimit sets the scan limit. Maximum is 8.
// Example: a 4 digit 7SegmentDisplay has a scan limit of 4
func (driver *Device) SetScanLimit(digitNumber uint8) {
driver.WriteCommand(byte(REG_SCANLIMIT), byte(digitNumber-1))
}
// SetDecodeMode sets the decode mode for 7 segment displays.
// digitNumber = 1 -> 1 digit gets decoded
// digitNumber = 2 or 3, or 4 -> 4 digit are being decoded
// digitNumber = 8 -> 8 digits are being decoded
// digitNumber 0 || digitNumber > 8 -> no decoding is being used
func (driver *Device) SetDecodeMode(digitNumber uint8) {
switch digitNumber {
case 1: // only decode first digit
driver.WriteCommand(REG_DECODE_MODE, 0x01)
case 2, 3, 4: // decode digits 3-0
driver.WriteCommand(REG_DECODE_MODE, 0x0F)
case 8: // decode 8 digits
driver.WriteCommand(REG_DECODE_MODE, 0xFF)
default:
driver.WriteCommand(REG_DECODE_MODE, 0x00)
}
}
// StartShutdownMode sets the IC into a low power shutdown mode.
func (driver *Device) StartShutdownMode() {
driver.WriteCommand(REG_SHUTDOWN, 0x00)
}
// StartShutdownMode sets the IC into normal operation mode.
func (driver *Device) StopShutdownMode() {
driver.WriteCommand(REG_SHUTDOWN, 0x01)
}
// StartDisplayTest starts a display test.
func (driver *Device) StartDisplayTest() {
driver.WriteCommand(REG_DISPLAY_TEST, 0x01)
}
// StopDisplayTest stops the display test and gets into normal operation mode.
func (driver *Device) StopDisplayTest() {
driver.WriteCommand(REG_DISPLAY_TEST, 0x00)
}
func (driver *Device) writeByte(data byte) {
driver.bus.Transfer(data)
}
// WriteCommand write data to a given register.
func (driver *Device) WriteCommand(register, data byte) {
driver.cs.Low()
driver.writeByte(register)
driver.writeByte(data)
driver.cs.High()
}