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machine: add KHz, MHz, GHz constants, deprecate TWI_FREQ_* constants

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There are two main issues with these constants:

  * They don't follow the Go naming convention.
  * They call themselves "TWI", while it makes a lot more sense to refer
    to the actual name which is I2C (or I²C).

I have not removed them but just deprecated them. Perhaps we can remove
them when we move towards version 1.0.
This commit is contained in:
Ayke van Laethem
2022-09-16 13:50:48 +02:00
committed by Ron Evans
parent bc946f346d
commit 7513fa2c96
11 changed files with 24 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/machine/machine_mimxrt1062_i2c.go
+7 -16
View File
@@ -10,15 +10,6 @@ import (
"errors"
)
const (
TWI_FREQ_BUS = 24000000 // LPI2C root clock is on 24 MHz OSC
TWI_FREQ_100KHZ = 100000 // StandardMode (100 kHz)
TWI_FREQ_400KHZ = 400000 // FastMode (400 kHz)
TWI_FREQ_1MHZ = 1000000 // FastModePlus (1 MHz)
TWI_FREQ_5MHZ = 5000000 // UltraFastMode (5 MHz)
TWI_FREQ_DEFAULT = TWI_FREQ_100KHZ // default to StandardMode (100 kHz)
)
var (
errI2CWriteTimeout = errors.New("I2C timeout during write")
errI2CReadTimeout = errors.New("I2C timeout during read")
@@ -174,7 +165,7 @@ func (i2c *I2C) Configure(config I2CConfig) {
freq := config.Frequency
if 0 == freq {
freq = TWI_FREQ_DEFAULT
freq = 100 * KHz
}
// reset clock and registers, and enable LPI2C module interface
@@ -305,7 +296,7 @@ func (i2c *I2C) setFrequency(freq uint32) {
wasEnabled := i2c.Bus.MCR.HasBits(nxp.LPI2C_MCR_MEN)
i2c.Bus.MCR.ClearBits(nxp.LPI2C_MCR_MEN)
// baud rate = (TWI_FREQ_BUS/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
// baud rate = (24MHz/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
// assume: CLKLO=2*CLKHI, SETHOLD=CLKHI, DATAVD=CLKHI/2
for pre := uint32(1); pre <= 128; pre *= 2 {
if bestError == 0 {
@@ -314,9 +305,9 @@ func (i2c *I2C) setFrequency(freq uint32) {
for clkHi := uint32(1); clkHi < 32; clkHi++ {
var absError, rate uint32
if clkHi == 1 {
rate = (TWI_FREQ_BUS / pre) / (1 + 3 + 2 + 2/pre)
rate = (24 * MHz / pre) / (1 + 3 + 2 + 2/pre)
} else {
rate = (TWI_FREQ_BUS / pre) / (3*clkHi + 2 + 2/pre)
rate = (24 * MHz / pre) / (3*clkHi + 2 + 2/pre)
}
if freq > rate {
absError = freq - rate
@@ -370,15 +361,15 @@ func (i2c *I2C) setFrequency(freq uint32) {
mcfgr2, mcfgr3 uint32
)
const i2cClockStretchTimeout = 15000 // microseconds
if freq >= TWI_FREQ_5MHZ {
if freq >= 5*MHz {
// I2C UltraFastMode 5 MHz
mcfgr2 = 0 // disable glitch filters and timeout for UltraFastMode
mcfgr3 = 0 //
} else if freq >= TWI_FREQ_1MHZ {
} else if freq >= 1*MHz {
// I2C FastModePlus 1 MHz
mcfgr2 = filtsda(1) | filtscl(1) | busidle(2400) // 100us timeout
mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
} else if freq >= TWI_FREQ_400KHZ {
} else if freq >= 400*KHz {
// I2C FastMode 400 kHz
mcfgr2 = filtsda(2) | filtscl(2) | busidle(3600) // 150us timeout
mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)