diff --git a/rp2040_uart/2024-03_rp2040-uart.md b/rp2040_uart/2024-03_rp2040-uart.md
index 7ac78ee5a395458bcb69c8c3624397c4bc72143c..45fe1e4c9c285c797ae047d28206d03d274b417d 100644
--- a/rp2040_uart/2024-03_rp2040-uart.md
+++ b/rp2040_uart/2024-03_rp2040-uart.md
@@ -61,9 +61,17 @@ Not totally sure, but I'm going to move on to try out Earle's software serial PI
So - let's try this out.
-OK, my big dawg `earle` looks to have this locked down, it is werken. It's also wrapped in the arduino Serial API meaning I could use 'em in an abstracted class for P2P comms. Bless his heart, now I need to check i.e. continuity and make some measurements...
+OK, I have this up and running: I am streaming at a fixed BAUD, then counting the ratio of bytes we miss in a stream. The uc's are counting missed and proper bytes (reading monotonic sequence numbers) and then checking also intervals between transmissions...
-Ah, jesus, nevermind, it is catching garbage bytes... all 255's, and it's reporting new-byteness when in fact none are visible on the line.
+| Mbit/s | Misses (errs / total-bytes) | Expected Byte Time (us) | Avg Byte Time |
+| --- | --- | --- | --- |
+| 0.1 | nil | 100 | 110.2 |
+| 0.5 | nil | 20 | 22.2 |
+| 1.0 | 0.025 (1/40) (!) | 10 | 13.4 |
+| 2.5 | 0.497 | 4 | 11.0 |
+| 5.0 | 0.755 | 2 | 11.0 |
+
+So, I'm not convinced that I haven't fuxd anything here... it seems wild that we would have such a bottleneck to performance, and there are a few red flags here; namely that we have a lower bound of 11us between transmits, which would also explain our increasing error rate when we surpass 1 Mbit/sec (as the byte-wise period there is 10us or so).
---
diff --git a/rp2040_uart/code/uart_pio_earle_rx/uart_pio_earle_rx.ino b/rp2040_uart/code/uart_pio_earle_rx/uart_pio_earle_rx.ino
deleted file mode 100644
index 1592a923273ded26d1be6a3ade3e9d1d6f640f0a..0000000000000000000000000000000000000000
--- a/rp2040_uart/code/uart_pio_earle_rx/uart_pio_earle_rx.ino
+++ /dev/null
@@ -1,71 +0,0 @@
-#include "screen.h"
-
-// using an RP2040 XIAO
-// with earle philhower core
-
-// "D10" - GPIO 3
-#define PIN_DEBUG 3
-
-// on XIAO "RX" - GPIO 1
-#define PIN_RX 1
-#define PIO_BAUD 1000000
-
-SerialPIO serial(SerialPIO::NOPIN, PIN_RX);
-
-void setup(void){
- pinMode(PIN_LED_B, OUTPUT);
- digitalWrite(PIN_LED_B, LOW);
-
- pinMode(PIN_DEBUG, OUTPUT);
- digitalWrite(PIN_DEBUG, LOW);
-
- // the display setup
- displaySetup();
- displayPrint("bonjour...");
-
- serial.begin(PIO_BAUD);
-}
-
-uint32_t lastUpdate = 0;
-uint32_t updateInterval = 200;
-
-uint8_t expectedRx = 0;
-uint32_t missCount = 0;
-uint32_t catchCount = 0;
-
-uint8_t chars[256];
-
-void loop(void){
- if(serial.available()){
- // earle core throws -1 if we have an error,
- int data = serial.read();
- if(data < 0) {
- return;
- }
- // count total hits
- catchCount ++;
- // catch data and count sequence errors
- digitalWrite(PIN_DEBUG, !digitalRead(PIN_DEBUG));
- chars[catchCount & 255] = data;
- if(data != expectedRx){
- missCount ++;
- }
- expectedRx = data + 1;
- }
- // uint8_t data = uart_rx_program_getc(pio, sm);
- // digitalWrite(PIN_DEBUG, LOW);
- // ...
- if(lastUpdate + updateInterval < millis()){
- lastUpdate = millis();
- digitalWrite(PIN_LED_B, !digitalRead(PIN_LED_B));
- displayPrint(String(missCount) + " / " + String(catchCount) + " \n" +
- String(chars[0]) + ", " + String(chars[1]) + ", " + String(chars[2]) + ", " + String(chars[3]) + ", " + String(chars[4]) + ", " + String(chars[5]) + ", "
- );
-
- // displayPrint(spipi_print());
- // displayPrint(String(rxCount) + "\n" +
- // String(rxSize)
- // );
- }
-}
-
diff --git a/rp2040_uart/code/uart_pio_earle_rx/screen.cpp b/rp2040_uart/code/uart_pio_earle_tx_rx/screen.cpp
similarity index 100%
rename from rp2040_uart/code/uart_pio_earle_rx/screen.cpp
rename to rp2040_uart/code/uart_pio_earle_tx_rx/screen.cpp
diff --git a/rp2040_uart/code/uart_pio_earle_rx/screen.h b/rp2040_uart/code/uart_pio_earle_tx_rx/screen.h
similarity index 100%
rename from rp2040_uart/code/uart_pio_earle_rx/screen.h
rename to rp2040_uart/code/uart_pio_earle_tx_rx/screen.h
diff --git a/rp2040_uart/code/uart_pio_earle_tx_rx/uart_pio_earle_tx_rx.ino b/rp2040_uart/code/uart_pio_earle_tx_rx/uart_pio_earle_tx_rx.ino
new file mode 100644
index 0000000000000000000000000000000000000000..6d34a41dd5ac6563ef1d72a8ea76220e9c3ad62c
--- /dev/null
+++ b/rp2040_uart/code/uart_pio_earle_tx_rx/uart_pio_earle_tx_rx.ino
@@ -0,0 +1,102 @@
+#include "screen.h"
+
+// using an RP2040 XIAO
+// with earle philhower core
+
+// "D10" - GPIO 3
+#define PIN_DEBUG 3
+
+#define PIN_RX 1
+#define PIN_TX 0
+#define PIO_BAUD 2500000
+
+SerialPIO serial(PIN_TX, PIN_RX);
+
+void setup(void){
+ pinMode(PIN_LED_B, OUTPUT);
+ digitalWrite(PIN_LED_B, LOW);
+
+ pinMode(PIN_DEBUG, OUTPUT);
+ digitalWrite(PIN_DEBUG, LOW);
+
+ // the display setup
+ displaySetup();
+ displayPrint("bonjour...");
+
+ serial.begin(PIO_BAUD);
+}
+
+uint32_t lastUpdate = 0;
+uint32_t updateInterval = 1000;
+
+uint8_t expectedRx = 0;
+uint32_t missCount = 0;
+uint32_t catchCount = 0;
+
+uint8_t expected_miss = 0;
+uint8_t actual_miss = 0;
+
+uint8_t chars[256];
+
+uint8_t seqNum = 0;
+
+// and let's calculate actual bandwidth (success bytes / sec * 8) and bitrate ( * 10)
+// and record avg per-cycle pickup ?
+
+uint32_t lastTx = 0;
+float intervalEstimate = 0.0F;
+
+void loop(void){
+
+ // catch 'em AFAP
+ if(serial.available()){
+ while(serial.available()){
+ int data = serial.read();
+ // earle core throws -1 if we have an error,
+ if(data < 0) {
+ return;
+ }
+ // count total hits
+ catchCount ++;
+ // stuff it
+ chars[catchCount & 255] = data;
+ // check for missus
+ if(data != expectedRx){
+ actual_miss = data;
+ expected_miss = expectedRx;
+ missCount ++;
+ }
+ expectedRx = data + 1;
+ }
+ }
+
+ // and write AFAP, recording outgoing times
+ if(serial.availableForWrite()){
+ digitalWrite(PIN_DEBUG, !digitalRead(PIN_DEBUG));
+ serial.write(seqNum ++);
+ uint32_t txTime = micros();
+ uint32_t txInterval = txTime - lastTx;
+ lastTx = txTime;
+ intervalEstimate = (float)txInterval * 0.01F + intervalEstimate * 0.99F;
+ // while(serial.availableForWrite()){
+ // }
+ }
+
+ // ...
+ if(lastUpdate + updateInterval < millis()){
+ lastUpdate = millis();
+ digitalWrite(PIN_LED_B, !digitalRead(PIN_LED_B));
+ displayPrint(String(missCount) + " / " + String(catchCount) + " \n" +
+ "miss: " + String((float)missCount / (float)catchCount, 9) + "\n" +
+ String(expected_miss) + ": " + String(actual_miss) + "\n" +
+ "avg interval: " + String(intervalEstimate, 4)
+ // String(chars[0]) + ", " + String(chars[1]) + ", " + String(chars[2]) + ", " + String(chars[3]) + ", " + String(chars[4]) + ", " + String(chars[5]) + ", "
+ );
+
+ // displayPrint(spipi_print());
+ // displayPrint(String(rxCount) + "\n" +
+ // String(rxSize)
+ // );
+ }
+}
+