tinygo-org/drivers
1
0
Fork 0
mirror of https://github.com/tinygo-org/drivers.git synced 2026-07-26 10:38:41 +00:00
Code Issues Packages Projects Releases 10 Wiki Activity

bmi160: avoid heap allocations

Browse Source 
The nrf52 series chips use DMA for writing and reading SPI data, which
means that the transmit and receive buffer slices escape. This can
easily be solved by pre-allocating the buffer in the BMI160 driver and
reusing this buffer every time.
This commit is contained in:
Ayke van Laethem
2021-05-30 18:06:47 +02:00
committed by Ron Evans
parent 9adbde99a2
commit 5ecefde991
1 changed files with 24 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
bmi160/bmi160.go
+24 -5
View File
@@ -13,6 +13,8 @@ type DeviceSPI struct {
// Chip select pin
CSB machine.Pin
buf [7]byte
// SPI bus (requires chip select to be usable).
Bus drivers.SPI
}
@@ -80,7 +82,10 @@ func (d *DeviceSPI) Reset() error {
// ReadTemperature returns the temperature in celsius milli degrees (°C/1000).
func (d *DeviceSPI) ReadTemperature() (temperature int32, err error) {
data := []byte{0x80 | reg_TEMPERATURE_0, 0, 0}
data := d.buf[:3]
data[0] = 0x80 | reg_TEMPERATURE_0
data[1] = 0
data[2] = 0
d.CSB.Low()
err = d.Bus.Tx(data, data)
d.CSB.High()
@@ -113,7 +118,11 @@ func (d *DeviceSPI) ReadTemperature() (temperature int32, err error) {
// and the sensor is not moving the returned value will be around 1000000 or
// -1000000.
func (d *DeviceSPI) ReadAcceleration() (x int32, y int32, z int32, err error) {
data := []byte{0x80 | reg_ACC_XL, 0, 0, 0, 0, 0, 0}
data := d.buf[:7]
data[0] = 0x80 | reg_ACC_XL
for i := 1; i < len(data); i++ {
data[i] = 0
}
d.CSB.Low()
err = d.Bus.Tx(data, data)
d.CSB.High()
@@ -139,7 +148,11 @@ func (d *DeviceSPI) ReadAcceleration() (x int32, y int32, z int32, err error) {
// rotation along one axis and while doing so integrate all values over time,
// you would get a value close to 360000000.
func (d *DeviceSPI) ReadRotation() (x int32, y int32, z int32, err error) {
data := []byte{0x80 | reg_GYR_XL, 0, 0, 0, 0, 0, 0}
data := d.buf[:7]
data[0] = 0x80 | reg_GYR_XL
for i := 1; i < len(data); i++ {
data[i] = 0
}
d.CSB.Low()
err = d.Bus.Tx(data, data)
d.CSB.High()
@@ -185,7 +198,9 @@ func (d *DeviceSPI) readRegister(address uint8) uint8 {
// I don't know why but it appears necessary to sleep for a bit here.
time.Sleep(time.Millisecond)
data := []byte{0x80 | address, 0}
data := d.buf[:2]
data[0] = 0x80 | address
data[1] = 0
d.CSB.Low()
d.Bus.Tx(data, data)
d.CSB.High()
@@ -198,7 +213,11 @@ func (d *DeviceSPI) writeRegister(address, data uint8) {
// I don't know why but it appears necessary to sleep for a bit here.
time.Sleep(time.Millisecond)
buf := d.buf[:2]
buf[0] = address
buf[1] = data
d.CSB.Low()
d.Bus.Tx([]byte{address, data}, []byte{0, 0})
d.Bus.Tx(buf, buf)
d.CSB.High()
}