Skip to content

NXP targets: Improved baudrate calculation function #116

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Dec 2, 2013
Merged

NXP targets: Improved baudrate calculation function #116

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -124,22 +124,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -121,22 +121,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -124,22 +124,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -157,22 +157,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -156,22 +156,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
57 changes: 41 additions & 16 deletions libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -147,22 +147,47 @@ void serial_baud(serial_t *obj, int baudrate) {
uint16_t dlv;
uint8_t mv, dav;
if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
float err_best = (float) baudrate;
uint16_t dlmax = DL;
for ( dlv = (dlmax/2); (dlv <= dlmax) && !hit; dlv++) {
for ( mv = 1; mv <= 15; mv++) {
for ( dav = 1; dav < mv; dav++) {
float ratio = 1.0f + ((float) dav / (float) mv);
float calcbaud = (float)PCLK / (16.0f * (float) dlv * ratio);
float err = fabs(((float) baudrate - calcbaud) / (float) baudrate);
if (err < err_best) {
DL = dlv;
DivAddVal = dav;
MulVal = mv;
err_best = err;
if (err < 0.001f) {
hit = 1;
}
int err_best = baudrate, b;
for (mv = 1; mv < 16 && !hit; mv++)
{
for (dav = 0; dav < mv; dav++)
{
// baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
// solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
// mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
// for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
// note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding

if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
else // 2 bits headroom, use more precision
dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;

// datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
if (dlv == 0)
dlv = 1;

// datasheet says if dav > 0 then DL must be >= 2
if ((dav > 0) && (dlv < 2))
dlv = 2;

// integer rearrangement of the baudrate equation (with rounding)
b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;

// check to see how we went
b = abs(b - baudrate);
if (b < err_best)
{
err_best = b;

DL = dlv;
MulVal = mv;
DivAddVal = dav;

if (b == baudrate)
{
hit = 1;
break;
}
}
}
Expand Down
Loading